diff --git a/src/sage/algebras/free_algebra_quotient_element.py b/src/sage/algebras/free_algebra_quotient_element.py
index c4ade5274b2..0523ff4b9dc 100644
--- a/src/sage/algebras/free_algebra_quotient_element.py
+++ b/src/sage/algebras/free_algebra_quotient_element.py
@@ -38,6 +38,10 @@ def is_FreeAlgebraQuotientElement(x):
 
         sage: H, (i,j,k) = sage.algebras.free_algebra_quotient.hamilton_quatalg(QQ)
         sage: sage.algebras.free_algebra_quotient_element.is_FreeAlgebraQuotientElement(i)
+        doctest:warning...
+        DeprecationWarning: The function is_FreeAlgebraQuotientElement is deprecated;
+        use 'isinstance(..., FreeAlgebraQuotientElement)' instead.
+        See https://github.com/sagemath/sage/issues/38184 for details.
         True
 
     Of course this is testing the data type::
@@ -47,6 +51,10 @@ def is_FreeAlgebraQuotientElement(x):
         sage: sage.algebras.free_algebra_quotient_element.is_FreeAlgebraQuotientElement(H(1))
         True
     """
+    from sage.misc.superseded import deprecation
+    deprecation(38184,
+                "The function is_FreeAlgebraQuotientElement is deprecated; "
+                "use 'isinstance(..., FreeAlgebraQuotientElement)' instead.")
     return isinstance(x, FreeAlgebraQuotientElement)
 
 
diff --git a/src/sage/categories/functor.pyx b/src/sage/categories/functor.pyx
index 5e3262c8dd3..2ca369c2ef5 100644
--- a/src/sage/categories/functor.pyx
+++ b/src/sage/categories/functor.pyx
@@ -96,15 +96,15 @@ cdef class Functor(SageObject):
         Category of rings
         sage: F.codomain()
         Category of commutative additive groups
-        sage: from sage.categories.functor import is_Functor
-        sage: is_Functor(F)
+        sage: from sage.categories.functor import Functor
+        sage: isinstance(F, Functor)
         True
         sage: I = IdentityFunctor(abgrps)
         sage: I
         The identity functor on Category of commutative additive groups
         sage: I.domain()
         Category of commutative additive groups
-        sage: is_Functor(I)
+        sage: isinstance(I, Functor)
         True
 
     Note that by default, an instance of the class Functor is coercion
@@ -422,12 +422,9 @@ cdef class Functor(SageObject):
 
 def is_Functor(x):
     """
-    Test whether the argument is a functor
-
-    NOTE:
+    Test whether the argument is a functor.
 
-    There is a deprecation warning when using it from top level.
-    Therefore we import it in our doc test.
+    This function is deprecated.
 
     EXAMPLES::
 
@@ -436,6 +433,10 @@ def is_Functor(x):
         sage: F1
         FractionField
         sage: is_Functor(F1)
+        doctest:warning...
+        DeprecationWarning: The function is_Functor is deprecated;
+        use 'isinstance(..., Functor)' instead.
+        See https://github.com/sagemath/sage/issues/38184 for details.
         True
         sage: is_Functor(FractionField)
         False
@@ -446,6 +447,10 @@ def is_Functor(x):
         True
 
     """
+    from sage.misc.superseded import deprecation
+    deprecation(38184,
+                "The function is_Functor is deprecated; "
+                "use 'isinstance(..., Functor)' instead.")
     return isinstance(x, Functor)
 
 
diff --git a/src/sage/groups/abelian_gps/abelian_group_element.py b/src/sage/groups/abelian_gps/abelian_group_element.py
index ac279f71011..172a671906c 100644
--- a/src/sage/groups/abelian_gps/abelian_group_element.py
+++ b/src/sage/groups/abelian_gps/abelian_group_element.py
@@ -57,11 +57,19 @@ def is_AbelianGroupElement(x):
 
         sage: from sage.groups.abelian_gps.abelian_group_element import is_AbelianGroupElement
         sage: is_AbelianGroupElement(3)
+        doctest:warning...
+        DeprecationWarning: The function is_AbelianGroupElement is deprecated;
+        use 'isinstance(..., AbelianGroupElement)' instead.
+        See https://github.com/sagemath/sage/issues/38184 for details.
         False
         sage: F = AbelianGroup(5, [3,4,5,8,7], 'abcde')
         sage: is_AbelianGroupElement(F.0)
         True
     """
+    from sage.misc.superseded import deprecation
+    deprecation(38184,
+                "The function is_AbelianGroupElement is deprecated; "
+                "use 'isinstance(..., AbelianGroupElement)' instead.")
     return isinstance(x, AbelianGroupElement)
 
 
diff --git a/src/sage/groups/abelian_gps/dual_abelian_group.py b/src/sage/groups/abelian_gps/dual_abelian_group.py
index 24c910d96d9..aaa231b0f81 100644
--- a/src/sage/groups/abelian_gps/dual_abelian_group.py
+++ b/src/sage/groups/abelian_gps/dual_abelian_group.py
@@ -345,7 +345,7 @@ def __contains__(self, X):
             sage: A*B^2*D^7 in Fd
             True
         """
-        return X.parent() == self and is_DualAbelianGroupElement(X)
+        return X.parent() == self and isinstance(X, DualAbelianGroupElement)
 
     def order(self):
         """
diff --git a/src/sage/groups/abelian_gps/dual_abelian_group_element.py b/src/sage/groups/abelian_gps/dual_abelian_group_element.py
index ecf17404bdd..048666b020f 100644
--- a/src/sage/groups/abelian_gps/dual_abelian_group_element.py
+++ b/src/sage/groups/abelian_gps/dual_abelian_group_element.py
@@ -71,10 +71,18 @@ def is_DualAbelianGroupElement(x) -> bool:
         sage: from sage.groups.abelian_gps.dual_abelian_group import is_DualAbelianGroupElement
         sage: F = AbelianGroup(5, [5,5,7,8,9], names=list("abcde")).dual_group()
         sage: is_DualAbelianGroupElement(F)
+        doctest:warning...
+        DeprecationWarning: The function is_DualAbelianGroupElement is deprecated;
+        use 'isinstance(..., DualAbelianGroupElement)' instead.
+        See https://github.com/sagemath/sage/issues/38184 for details.
         False
         sage: is_DualAbelianGroupElement(F.an_element())
         True
     """
+    from sage.misc.superseded import deprecation
+    deprecation(38184,
+                "The function is_DualAbelianGroupElement is deprecated; "
+                "use 'isinstance(..., DualAbelianGroupElement)' instead.")
     return isinstance(x, DualAbelianGroupElement)
 
 
diff --git a/src/sage/groups/perm_gps/permgroup_element.pyx b/src/sage/groups/perm_gps/permgroup_element.pyx
index c6eb59df19f..4d6a67fe41b 100644
--- a/src/sage/groups/perm_gps/permgroup_element.pyx
+++ b/src/sage/groups/perm_gps/permgroup_element.pyx
@@ -211,8 +211,16 @@ def is_PermutationGroupElement(x):
         sage: p = PermutationGroupElement([(1,2),(3,4,5)])
         sage: from sage.groups.perm_gps.permgroup_element import is_PermutationGroupElement
         sage: is_PermutationGroupElement(p)
+        doctest:warning...
+        DeprecationWarning: The function is_PermutationGroupElement is deprecated;
+        use 'isinstance(..., PermutationGroupElement)' instead.
+        See https://github.com/sagemath/sage/issues/38184 for details.
         True
     """
+    from sage.misc.superseded import deprecation_cython
+    deprecation_cython(38184,
+                       "The function is_PermutationGroupElement is deprecated; "
+                       "use 'isinstance(..., PermutationGroupElement)' instead.")
     return isinstance(x, PermutationGroupElement)
 
 
diff --git a/src/sage/homology/chain_complex_homspace.py b/src/sage/homology/chain_complex_homspace.py
index cf981d76561..1170b50b885 100644
--- a/src/sage/homology/chain_complex_homspace.py
+++ b/src/sage/homology/chain_complex_homspace.py
@@ -116,9 +116,17 @@ def is_ChainComplexHomspace(x):
         sage: C = T.chain_complex(augmented=True, cochain=True)
         sage: G = Hom(C, C)
         sage: is_ChainComplexHomspace(G)
+        doctest:warning...
+        DeprecationWarning: The function is_ChainComplexHomspace is deprecated;
+        use 'isinstance(..., ChainComplexHomspace)' instead.
+        See https://github.com/sagemath/sage/issues/38184 for details.
         True
 
     """
+    from sage.misc.superseded import deprecation
+    deprecation(38184,
+                "The function is_ChainComplexHomspace is deprecated; "
+                "use 'isinstance(..., ChainComplexHomspace)' instead.")
     return isinstance(x, ChainComplexHomspace)
 
 
diff --git a/src/sage/matrix/matrix2.pyx b/src/sage/matrix/matrix2.pyx
index e452b51fc82..0b51d5c1df7 100644
--- a/src/sage/matrix/matrix2.pyx
+++ b/src/sage/matrix/matrix2.pyx
@@ -99,7 +99,7 @@ from sage.arith.numerical_approx cimport digits_to_bits
 
 import sage.modules.free_module
 from sage.matrix import berlekamp_massey
-from sage.modules.free_module_element import is_FreeModuleElement
+from sage.modules.free_module_element import FreeModuleElement
 from sage.matrix.matrix_misc import permanental_minor_polynomial
 
 from sage.misc.misc_c import prod
@@ -6153,7 +6153,7 @@ cdef class Matrix(Matrix1):
         """
         if v == 0:
             return []
-        if not is_FreeModuleElement(v):
+        if not isinstance(v, FreeModuleElement):
             raise TypeError("v must be a FreeModuleElement")
         VS = v.parent()
         V = VS.span([v])
diff --git a/src/sage/misc/latex.py b/src/sage/misc/latex.py
index 9c2af93adeb..422aa90b89b 100644
--- a/src/sage/misc/latex.py
+++ b/src/sage/misc/latex.py
@@ -1934,7 +1934,7 @@ def png(x, filename, density=150, debug=False,
         ....:     png(ZZ[x], f.name)
     """
     import sage.plot.all
-    if sage.plot.graphics.is_Graphics(x):
+    if isinstance(x, sage.plot.graphics.Graphics):
         x.save(filename)
         return
     # if not graphics: create a string of latex code to write in a file
diff --git a/src/sage/modular/dirichlet.py b/src/sage/modular/dirichlet.py
index 4d0436bad22..e579c5090e3 100644
--- a/src/sage/modular/dirichlet.py
+++ b/src/sage/modular/dirichlet.py
@@ -172,10 +172,18 @@ def is_DirichletCharacter(x) -> bool:
 
         sage: from sage.modular.dirichlet import is_DirichletCharacter
         sage: is_DirichletCharacter(trivial_character(3))
+        doctest:warning...
+        DeprecationWarning: The function is_DirichletCharacter is deprecated;
+        use 'isinstance(..., DirichletCharacter)' instead.
+        See https://github.com/sagemath/sage/issues/38184 for details.
         True
         sage: is_DirichletCharacter([1])
         False
     """
+    from sage.misc.superseded import deprecation
+    deprecation(38184,
+                "The function is_DirichletCharacter is deprecated; "
+                "use 'isinstance(..., DirichletCharacter)' instead.")
     return isinstance(x, DirichletCharacter)
 
 
@@ -262,7 +270,7 @@ def __init__(self, parent, x, check=True):
             orders = parent.integers_mod().unit_group().gens_orders()
             if len(x) != len(orders):
                 raise ValueError("wrong number of values (= {}) on generators (want {})".format(x, len(orders)))
-            if free_module_element.is_FreeModuleElement(x):
+            if isinstance(x, free_module_element.FreeModuleElement):
                 x = parent._module(x)
                 if any(u * v for u, v in zip(x, orders)):
                     raise ValueError("values (= {} modulo {}) must have additive orders dividing {}, respectively"
@@ -276,7 +284,7 @@ def __init__(self, parent, x, check=True):
                                      .format(x, orders))
                 self.values_on_gens.set_cache(x)
         else:
-            if free_module_element.is_FreeModuleElement(x):
+            if isinstance(x, free_module_element.FreeModuleElement):
                 self.element.set_cache(x)
             else:
                 self.values_on_gens.set_cache(x)
diff --git a/src/sage/modular/modform/ambient_eps.py b/src/sage/modular/modform/ambient_eps.py
index 1d42305436c..81527a72aa8 100644
--- a/src/sage/modular/modform/ambient_eps.py
+++ b/src/sage/modular/modform/ambient_eps.py
@@ -124,7 +124,7 @@ def __init__(self, character, weight=2, base_ring=None, eis_only=False):
             sage: type(m)
             <class 'sage.modular.modform.ambient_eps.ModularFormsAmbient_eps_with_category'>
         """
-        if not dirichlet.is_DirichletCharacter(character):
+        if not isinstance(character, dirichlet.DirichletCharacter):
             raise TypeError("character (=%s) must be a Dirichlet character" % character)
         if base_ring is None:
             base_ring = character.base_ring()
diff --git a/src/sage/modular/modform/element.py b/src/sage/modular/modform/element.py
index aa859d9c38c..72880952610 100644
--- a/src/sage/modular/modform/element.py
+++ b/src/sage/modular/modform/element.py
@@ -72,10 +72,18 @@ def is_ModularFormElement(x):
 
         sage: from sage.modular.modform.element import is_ModularFormElement
         sage: is_ModularFormElement(5)
+        doctest:warning...
+        DeprecationWarning: The function is_ModularFormElement is deprecated;
+        use 'isinstance(..., ModularFormElement)' instead.
+        See https://github.com/sagemath/sage/issues/38184 for details.
         False
         sage: is_ModularFormElement(ModularForms(11).0)
         True
     """
+    from sage.misc.superseded import deprecation
+    deprecation(38184,
+                "The function is_ModularFormElement is deprecated; "
+                "use 'isinstance(..., ModularFormElement)' instead.")
     return isinstance(x, ModularFormElement)
 
 
@@ -3265,7 +3273,7 @@ def __init__(self, parent, forms_datum):
                     k = ZZ(k)
                     if k == 0:
                         forms_dictionary[k] = parent.base_ring().coerce(f)
-                    elif is_ModularFormElement(f):
+                    elif isinstance(f, ModularFormElement):
                         if f.weight() == k:
                             if parent.group().is_subgroup(f.group()) and parent.base_ring().has_coerce_map_from(f.base_ring()):
                                 M = parent.modular_forms_of_weight(f.weight()).change_ring(parent.base_ring())
@@ -3280,7 +3288,7 @@ def __init__(self, parent, forms_datum):
                     raise ValueError('at least one key (%s) of the defining dictionary is not an integer' % (k))
         elif isinstance(forms_datum, list):
             for f in forms_datum:
-                if is_ModularFormElement(f):
+                if isinstance(f, ModularFormElement):
                     chi = f.character(compute=False)
                     if (chi is not None) and (not chi.is_trivial()):
                         raise NotImplementedError("graded modular forms for non-trivial characters is not yet implemented")
diff --git a/src/sage/modular/modform/hecke_operator_on_qexp.py b/src/sage/modular/modform/hecke_operator_on_qexp.py
index ea472bb4185..daf4c3bfbec 100644
--- a/src/sage/modular/modform/hecke_operator_on_qexp.py
+++ b/src/sage/modular/modform/hecke_operator_on_qexp.py
@@ -23,8 +23,8 @@
 
 lazy_import('sage.rings.number_field.number_field', 'CyclotomicField')
 
-from sage.modular.dirichlet import DirichletGroup, is_DirichletCharacter
-from .element import is_ModularFormElement
+from sage.modular.dirichlet import DirichletGroup, DirichletCharacter
+from .element import ModularFormElement
 
 def hecke_operator_on_qexp(f, n, k, eps=None,
                            prec=None, check=True, _return_list=False):
@@ -87,16 +87,16 @@ def hecke_operator_on_qexp(f, n, k, eps=None,
         # ZZ can coerce to GF(p), but QQ can't.
         eps = DirichletGroup(1, base_ring=ZZ)[0]
     if check:
-        if not (is_PowerSeries(f) or is_ModularFormElement(f)):
+        if not (is_PowerSeries(f) or isinstance(f, ModularFormElement)):
             raise TypeError("f (=%s) must be a power series or modular form" % f)
-        if not is_DirichletCharacter(eps):
+        if not isinstance(eps, DirichletCharacter):
             raise TypeError("eps (=%s) must be a Dirichlet character" % eps)
         k = Integer(k)
         n = Integer(n)
     v = []
 
     if prec is None:
-        if is_ModularFormElement(f):
+        if isinstance(f, ModularFormElement):
             # always want at least three coefficients, but not too many, unless
             # requested
             pr = max(f.prec(), f.parent().prec(), (n+1)*3)
@@ -123,7 +123,7 @@ def hecke_operator_on_qexp(f, n, k, eps=None,
             v.append(am)
     if _return_list:
         return v
-    if is_ModularFormElement(f):
+    if isinstance(f, ModularFormElement):
         R = f.parent()._q_expansion_ring()
     else:
         R = f.parent()
diff --git a/src/sage/modular/modform/ring.py b/src/sage/modular/modform/ring.py
index 897c4718107..bf7b10dc025 100644
--- a/src/sage/modular/modform/ring.py
+++ b/src/sage/modular/modform/ring.py
@@ -40,7 +40,7 @@
 from sage.structure.richcmp import richcmp_method, richcmp
 
 from .constructor import ModularForms
-from .element import is_ModularFormElement, GradedModularFormElement
+from .element import ModularFormElement, GradedModularFormElement
 from .space import ModularFormsSpace
 
 
@@ -517,7 +517,7 @@ def _element_constructor_(self, forms_datum):
             forms_dictionary = forms_datum
         elif isinstance(forms_datum, self.element_class):
             forms_dictionary = forms_datum._forms_dictionary
-        elif is_ModularFormElement(forms_datum):
+        elif isinstance(forms_datum, ModularFormElement):
             if self.group().is_subgroup(forms_datum.group()) and self.base_ring().has_coerce_map_from(forms_datum.base_ring()):
                 forms_dictionary = {forms_datum.weight(): forms_datum}
             else:
diff --git a/src/sage/modular/modform_hecketriangle/abstract_space.py b/src/sage/modular/modform_hecketriangle/abstract_space.py
index c2148a4e543..719d8847f31 100644
--- a/src/sage/modular/modform_hecketriangle/abstract_space.py
+++ b/src/sage/modular/modform_hecketriangle/abstract_space.py
@@ -17,7 +17,7 @@
 from sage.matrix.constructor import matrix
 from sage.misc.cachefunc import cached_method
 from sage.misc.lazy_import import lazy_import
-from sage.modules.free_module_element import is_FreeModuleElement
+from sage.modules.free_module_element import FreeModuleElement
 from sage.modules.free_module_element import vector
 from sage.rings.infinity import infinity
 from sage.rings.integer import Integer
@@ -262,9 +262,9 @@ def _element_constructor_(self, el):
                 return self.construct_form(el)
             else:
                 return self.construct_quasi_form(el)
-        if is_FreeModuleElement(el) and (self.module() is P or self.ambient_module() is P):
+        if isinstance(el, FreeModuleElement) and (self.module() is P or self.ambient_module() is P):
             return self.element_from_ambient_coordinates(el)
-        if (not self.is_ambient()) and (isinstance(el, list) or isinstance(el, tuple) or is_FreeModuleElement(el)) and len(el) == self.rank():
+        if (not self.is_ambient()) and (isinstance(el, list) or isinstance(el, tuple) or isinstance(el, FreeModuleElement)) and len(el) == self.rank():
             try:
                 return self.element_from_coordinates(el)
             except (ArithmeticError, TypeError):
diff --git a/src/sage/modular/modsym/ambient.py b/src/sage/modular/modsym/ambient.py
index 8585de56c46..02e1bc3cb9e 100644
--- a/src/sage/modular/modsym/ambient.py
+++ b/src/sage/modular/modsym/ambient.py
@@ -79,7 +79,7 @@ class ``ModularSymbolsAmbient``, derived from
 from sage.misc.latex import latex
 from sage.misc.verbose import verbose
 from sage.modular.arithgroup.arithgroup_element import M2Z
-from sage.modular.dirichlet import TrivialCharacter, is_DirichletCharacter
+from sage.modular.dirichlet import DirichletCharacter, TrivialCharacter
 from sage.modular.hecke.ambient_module import AmbientHeckeModule
 from sage.modular.cusps import Cusp
 from sage.modular.modsym.apply import apply_to_monomial
@@ -2171,7 +2171,7 @@ def twisted_winding_element(self, i, eps):
             sage: M.twisted_winding_element(0,eps)
             2*(1,23) - 2*(1,32) + 2*(1,34)
         """
-        if not is_DirichletCharacter(eps):
+        if not isinstance(eps, DirichletCharacter):
             raise TypeError("eps must be a Dirichlet character.")
         if (i < 0) or (i > self.weight() - 2):
             raise ValueError("i must be between 0 and k-2.")
diff --git a/src/sage/modular/modsym/boundary.py b/src/sage/modular/modsym/boundary.py
index 2076d81eb1e..093ba6a594f 100644
--- a/src/sage/modular/modsym/boundary.py
+++ b/src/sage/modular/modsym/boundary.py
@@ -93,7 +93,7 @@
 from sage.structure.richcmp import richcmp_method, richcmp
 
 import sage.modules.free_module as free_module
-from sage.modules.free_module_element import is_FreeModuleElement
+from sage.modules.free_module_element import FreeModuleElement
 
 import sage.modular.arithgroup.all as arithgroup
 import sage.modular.cusps as cusps
@@ -554,7 +554,7 @@ def __call__(self, x):
         elif isinstance(x, ManinSymbol):
             return self._coerce_in_manin_symbol(x)
 
-        elif element.is_ModularSymbolsElement(x):
+        elif isinstance(x, element.ModularSymbolsElement):
             M = x.parent()
             if not isinstance(M, ModularSymbolsAmbient):
                 raise TypeError("x (=%s) must be an element of a space of modular symbols of type ModularSymbolsAmbient" % x)
@@ -566,7 +566,7 @@ def __call__(self, x):
                 return self(0)
             return sum([c * self._coerce_in_manin_symbol(v) for c, v in S])
 
-        elif is_FreeModuleElement(x):
+        elif isinstance(x, FreeModuleElement):
             y = dict(enumerate(x))
             return BoundarySpaceElement(self, y)
 
diff --git a/src/sage/modular/modsym/element.py b/src/sage/modular/modsym/element.py
index 427d9218f8d..21b1ecb181b 100644
--- a/src/sage/modular/modsym/element.py
+++ b/src/sage/modular/modsym/element.py
@@ -36,10 +36,18 @@ def is_ModularSymbolsElement(x) -> bool:
     EXAMPLES::
 
         sage: sage.modular.modsym.element.is_ModularSymbolsElement(ModularSymbols(11, 2).0)
+        doctest:warning...
+        DeprecationWarning: The function is_ModularSymbolsElement is deprecated;
+        use 'isinstance(..., ModularSymbolsElement)' instead.
+        See https://github.com/sagemath/sage/issues/38184 for details.
         True
         sage: sage.modular.modsym.element.is_ModularSymbolsElement(13)
         False
     """
+    from sage.misc.superseded import deprecation
+    deprecation(38184,
+                "The function is_ModularSymbolsElement is deprecated; "
+                "use 'isinstance(..., ModularSymbolsElement)' instead.")
     return isinstance(x, ModularSymbolsElement)
 
 
diff --git a/src/sage/modular/modsym/manin_symbol.pyx b/src/sage/modular/modsym/manin_symbol.pyx
index 9bf955b562b..434aa370e18 100644
--- a/src/sage/modular/modsym/manin_symbol.pyx
+++ b/src/sage/modular/modsym/manin_symbol.pyx
@@ -43,10 +43,18 @@ def is_ManinSymbol(x):
         sage: s
         [Y^2,(1,2)]
         sage: is_ManinSymbol(s)
+        doctest:warning...
+        DeprecationWarning: The function is_ManinSymbol is deprecated;
+        use 'isinstance(..., ManinSymbol)' instead.
+        See https://github.com/sagemath/sage/issues/38184 for details.
         True
         sage: is_ManinSymbol(m[3])
         True
     """
+    from sage.misc.superseded import deprecation_cython
+    deprecation_cython(38184,
+                       "The function is_ManinSymbol is deprecated; "
+                       "use 'isinstance(..., ManinSymbol)' instead.")
     return isinstance(x, ManinSymbol)
 
 
diff --git a/src/sage/modules/free_module.py b/src/sage/modules/free_module.py
index f1c7c7cdbaa..6bf1b79bd7d 100644
--- a/src/sage/modules/free_module.py
+++ b/src/sage/modules/free_module.py
@@ -783,7 +783,7 @@ def span(gens, base_ring=None, check=True, already_echelonized=False):
         return FreeModule(R, 0)
     else:
         x = gens[0]
-        if free_module_element.is_FreeModuleElement(x):
+        if isinstance(x, free_module_element.FreeModuleElement):
             M = x.parent()
         else:
             try:
diff --git a/src/sage/modules/free_module_element.pyx b/src/sage/modules/free_module_element.pyx
index 4500695e297..d71d22ac1f7 100644
--- a/src/sage/modules/free_module_element.pyx
+++ b/src/sage/modules/free_module_element.pyx
@@ -139,10 +139,18 @@ def is_FreeModuleElement(x):
     EXAMPLES::
 
         sage: sage.modules.free_module_element.is_FreeModuleElement(0)
+        doctest:warning...
+        DeprecationWarning: The function is_FreeModuleElement is deprecated;
+        use 'isinstance(..., FreeModuleElement)' instead.
+        See https://github.com/sagemath/sage/issues/38184 for details.
         False
         sage: sage.modules.free_module_element.is_FreeModuleElement(vector([1,2,3]))
         True
     """
+    from sage.misc.superseded import deprecation_cython
+    deprecation_cython(38184,
+                       "The function is_FreeModuleElement is deprecated; "
+                       "use 'isinstance(..., FreeModuleElement)' instead.")
     return isinstance(x, FreeModuleElement)
 
 
diff --git a/src/sage/monoids/free_abelian_monoid_element.pyx b/src/sage/monoids/free_abelian_monoid_element.pyx
index c81c1fa5575..9f66e83942d 100644
--- a/src/sage/monoids/free_abelian_monoid_element.pyx
+++ b/src/sage/monoids/free_abelian_monoid_element.pyx
@@ -54,6 +54,10 @@ def is_FreeAbelianMonoidElement(x):
     - ``True`` if ``x`` is an object of type ``FreeAbelianMonoidElement``;
       ``False`` otherwise.
     """
+    from sage.misc.superseded import deprecation_cython
+    deprecation_cython(38184,
+                       "The function is_FreeAbelianMonoidElement is deprecated; "
+                       "use 'isinstance(..., FreeAbelianMonoidElement)' instead.")
     return isinstance(x, FreeAbelianMonoidElement)
 
 
diff --git a/src/sage/monoids/free_monoid_element.py b/src/sage/monoids/free_monoid_element.py
index 42d295eab76..993fef9c72d 100644
--- a/src/sage/monoids/free_monoid_element.py
+++ b/src/sage/monoids/free_monoid_element.py
@@ -30,6 +30,10 @@
 
 
 def is_FreeMonoidElement(x):
+    from sage.misc.superseded import deprecation
+    deprecation(38184,
+                "The function is_FreeMonoidElement is deprecated; "
+                "use 'isinstance(..., FreeMonoidElement)' instead.")
     return isinstance(x, FreeMonoidElement)
 
 
diff --git a/src/sage/numerical/linear_functions.pyx b/src/sage/numerical/linear_functions.pyx
index 3063ba7101d..d1a038fd54b 100644
--- a/src/sage/numerical/linear_functions.pyx
+++ b/src/sage/numerical/linear_functions.pyx
@@ -132,10 +132,18 @@ cpdef is_LinearFunction(x):
         sage: x = p.new_variable()
         sage: from sage.numerical.linear_functions import is_LinearFunction
         sage: is_LinearFunction(x[0] - 2*x[2])
+        doctest:warning...
+        DeprecationWarning: The function is_LinearFunction is deprecated;
+        use 'isinstance(..., LinearFunction)' instead.
+        See https://github.com/sagemath/sage/issues/38184 for details.
         True
         sage: is_LinearFunction('a string')
         False
     """
+    from sage.misc.superseded import deprecation_cython
+    deprecation_cython(38184,
+                       "The function is_LinearFunction is deprecated; "
+                       "use 'isinstance(..., LinearFunction)' instead.")
     return isinstance(x, LinearFunction)
 
 
@@ -158,10 +166,18 @@ def is_LinearConstraint(x):
         sage: ieq = (x[0] <= x[1])
         sage: from sage.numerical.linear_functions import is_LinearConstraint
         sage: is_LinearConstraint(ieq)
+        doctest:warning...
+        DeprecationWarning: The function is_LinearConstraint is deprecated;
+        use 'isinstance(..., LinearConstraint)' instead.
+        See https://github.com/sagemath/sage/issues/38184 for details.
         True
         sage: is_LinearConstraint('a string')
         False
     """
+    from sage.misc.superseded import deprecation_cython
+    deprecation_cython(38184,
+                       "The function is_LinearConstraint is deprecated; "
+                       "use 'isinstance(..., LinearConstraint)' instead.")
     return isinstance(x, LinearConstraint)
 
 
@@ -690,7 +706,7 @@ cdef class LinearFunctionsParent_class(Parent):
             sage: LF_QQ(f) is f
             False
         """
-        if is_LinearFunction(x):
+        if isinstance(x, LinearFunction):
             return LinearFunction(self, (<LinearFunction>x)._f)
         return LinearFunction(self, x)
 
@@ -891,7 +907,7 @@ cdef class LinearFunction(LinearFunctionOrConstraint):
             ...
             ValueError: x is from a different linear functions module
         """
-        if is_LinearFunction(x):
+        if isinstance(x, LinearFunction):
             if self.parent() != x.parent():
                 raise ValueError('x is from a different linear functions module')
             if len((<LinearFunction>x)._f) != 1:
@@ -1319,7 +1335,7 @@ cdef class LinearConstraintsParent_class(Parent):
             sage: LC_QQ(inequality) is inequality
             False
         """
-        if right is None and is_LinearConstraint(left):
+        if right is None and isinstance(left, LinearConstraint):
             if (left.parent() is self) and (left.is_equation() == equality):
                 return left
             else:
diff --git a/src/sage/numerical/linear_tensor.py b/src/sage/numerical/linear_tensor.py
index 217bd98f3bb..c4c62066db5 100644
--- a/src/sage/numerical/linear_tensor.py
+++ b/src/sage/numerical/linear_tensor.py
@@ -99,7 +99,7 @@
 
 from sage.structure.parent import Parent
 from sage.misc.cachefunc import cached_function
-from sage.numerical.linear_functions import is_LinearFunction, LinearFunctionsParent_class
+from sage.numerical.linear_functions import LinearFunction, LinearFunctionsParent_class
 from sage.numerical.linear_tensor_element import LinearTensor
 
 
@@ -128,10 +128,18 @@ def is_LinearTensor(x):
         sage: x = p.new_variable(nonnegative=False)
         sage: from sage.numerical.linear_tensor import is_LinearTensor
         sage: is_LinearTensor(x[0] - 2*x[2])
+        doctest:warning...
+        DeprecationWarning: The function is_LinearTensor is deprecated;
+        use 'isinstance(..., LinearTensor)' instead.
+        See https://github.com/sagemath/sage/issues/38184 for details.
         False
         sage: is_LinearTensor('a string')
         False
     """
+    from sage.misc.superseded import deprecation
+    deprecation(38184,
+                "The function is_LinearTensor is deprecated; "
+                "use 'isinstance(..., LinearTensor)' instead.")
     return isinstance(x, LinearTensor)
 
 
@@ -413,9 +421,9 @@ def _element_constructor_(self, x):
             (3.0, 3.0) + (2.0, 2.0)*x_1 + (1.0, 1.0)*x_3
         """
         M = self.free_module()
-        if is_LinearTensor(x):
+        if isinstance(x, LinearTensor):
             x = x.dict()
-        elif is_LinearFunction(x):
+        elif isinstance(x, LinearFunction):
             x = dict([key, self._convert_constant(value)] for key, value in x.dict().items())
         elif isinstance(x, dict):
             x = dict([int(key), M(value)] for key, value in x.items())
diff --git a/src/sage/numerical/linear_tensor_constraints.py b/src/sage/numerical/linear_tensor_constraints.py
index 24f94f3b3d6..60578c2511d 100644
--- a/src/sage/numerical/linear_tensor_constraints.py
+++ b/src/sage/numerical/linear_tensor_constraints.py
@@ -57,10 +57,18 @@ def is_LinearTensorConstraint(x):
         sage: vector_ieq = (x[0] * vector([1,2]) <= x[1] * vector([2,3]))
         sage: from sage.numerical.linear_tensor_constraints import is_LinearTensorConstraint
         sage: is_LinearTensorConstraint(vector_ieq)
+        doctest:warning...
+        DeprecationWarning: The function is_LinearTensorConstraint is deprecated;
+        use 'isinstance(..., LinearTensorConstraint)' instead.
+        See https://github.com/sagemath/sage/issues/38184 for details.
         True
         sage: is_LinearTensorConstraint('a string')
         False
     """
+    from sage.misc.superseded import deprecation
+    deprecation(38184,
+                "The function is_LinearTensorConstraint is deprecated; "
+                "use 'isinstance(..., LinearTensorConstraint)' instead.")
     return isinstance(x, LinearTensorConstraint)
 
 
diff --git a/src/sage/numerical/linear_tensor_element.pyx b/src/sage/numerical/linear_tensor_element.pyx
index c77aa290e21..f7dd2b61deb 100644
--- a/src/sage/numerical/linear_tensor_element.pyx
+++ b/src/sage/numerical/linear_tensor_element.pyx
@@ -169,7 +169,7 @@ cdef class LinearTensor(ModuleElement):
             ...
             ValueError: x is from a different linear functions module
         """
-        if is_LinearFunction(x):
+        if isinstance(x, LinearFunction):
             if self.parent().linear_functions() != x.parent():
                 raise ValueError('x is from a different linear functions module')
             if len((<LinearFunction>x)._f) != 1:
diff --git a/src/sage/numerical/mip.pyx b/src/sage/numerical/mip.pyx
index 2690172b85a..7af017ebd17 100644
--- a/src/sage/numerical/mip.pyx
+++ b/src/sage/numerical/mip.pyx
@@ -2134,14 +2134,14 @@ cdef class MixedIntegerLinearProgram(SageObject):
             sage: p.solve()
             6.0
         """
-        from sage.numerical.linear_functions import is_LinearFunction, is_LinearConstraint
-        from sage.numerical.linear_tensor import is_LinearTensor
-        from sage.numerical.linear_tensor_constraints import is_LinearTensorConstraint
-        if is_LinearFunction(linear_function) or is_LinearTensor(linear_function):
+        from sage.numerical.linear_functions import LinearFunction, LinearConstraint
+        from sage.numerical.linear_tensor import LinearTensor
+        from sage.numerical.linear_tensor_constraints import LinearTensorConstraint
+        if isinstance(linear_function, LinearFunction) or isinstance(linear_function, LinearTensor):
             # Find the parent for the coefficients
-            if is_LinearFunction(linear_function):
+            if isinstance(linear_function, LinearFunction):
                 M = linear_function.parent().base_ring()
-            elif is_LinearTensor(linear_function):
+            elif isinstance(linear_function, LinearTensor):
                 if not linear_function.parent().is_vector_space():
                     raise ValueError('the linear function must be vector-valued')
                 M = linear_function.parent().free_module()
@@ -2164,14 +2164,14 @@ cdef class MixedIntegerLinearProgram(SageObject):
             except KeyError:
                 pass
             # Send to backend
-            if is_LinearFunction(linear_function):
+            if isinstance(linear_function, LinearFunction):
                 if self._check_redundant and self._is_redundant_constraint(constraint, min, max):
                     if return_indices:
                         return []
                     return
                 nrows_before = self._backend.nrows()
                 self._backend.add_linear_constraint(constraint.items(), min, max, name)
-            elif is_LinearTensor(linear_function):
+            elif isinstance(linear_function, LinearTensor):
                 nrows_before = self._backend.nrows()
                 self._backend.add_linear_constraint_vector(M.degree(), constraint.items(), min, max, name)
             else:
@@ -2179,7 +2179,7 @@ cdef class MixedIntegerLinearProgram(SageObject):
             if return_indices:
                 return list(range(nrows_before, self._backend.nrows()))
             return
-        elif is_LinearConstraint(linear_function):
+        elif isinstance(linear_function, LinearConstraint):
             if not(min is None and max is None):
                 raise ValueError('min and max must not be specified for (in)equalities')
             relation = linear_function
@@ -2200,7 +2200,7 @@ cdef class MixedIntegerLinearProgram(SageObject):
                 if new_indices is not None:
                     row_indices.extend(new_indices)
             return row_indices
-        elif is_LinearTensorConstraint(linear_function):
+        elif isinstance(linear_function, LinearTensorConstraint):
             if not(min is None and max is None):
                 raise ValueError('min and max must not be specified for (in)equalities')
             relation = linear_function
diff --git a/src/sage/numerical/sdp.pyx b/src/sage/numerical/sdp.pyx
index 4f6f4db9291..7e214ad5023 100644
--- a/src/sage/numerical/sdp.pyx
+++ b/src/sage/numerical/sdp.pyx
@@ -233,7 +233,7 @@ AUTHORS:
 
 from sage.structure.parent cimport Parent
 from sage.structure.element cimport Element
-from sage.numerical.linear_functions import is_LinearFunction, is_LinearConstraint
+from sage.numerical.linear_functions import LinearFunction, LinearConstraint
 from sage.matrix.constructor import matrix
 from sage.structure.element import Matrix
 
@@ -895,10 +895,10 @@ cdef class SemidefiniteProgram(SageObject):
         if linear_function is 0:
             return
 
-        from sage.numerical.linear_tensor_constraints import is_LinearTensorConstraint
-        from sage.numerical.linear_tensor import is_LinearTensor
+        from sage.numerical.linear_tensor_constraints import LinearTensorConstraint
+        from sage.numerical.linear_tensor import LinearTensor
 
-        if is_LinearTensorConstraint(linear_function) or is_LinearConstraint(linear_function):
+        if isinstance(linear_function, LinearTensorConstraint) or isinstance(linear_function, LinearConstraint):
             c = linear_function
             if c.is_equation():
                 self.add_constraint(c.lhs()-c.rhs(), name=name)
@@ -906,7 +906,7 @@ cdef class SemidefiniteProgram(SageObject):
             else:
                 self.add_constraint(c.lhs()-c.rhs(), name=name)
 
-        elif is_LinearFunction(linear_function) or is_LinearTensor(linear_function):
+        elif isinstance(linear_function, LinearFunction) or isinstance(linear_function, LinearTensor):
             l = sorted(linear_function.dict().items())
             self._backend.add_linear_constraint(l, name)
 
diff --git a/src/sage/plot/graphics.py b/src/sage/plot/graphics.py
index 97d35e3ad54..a84d162cb56 100644
--- a/src/sage/plot/graphics.py
+++ b/src/sage/plot/graphics.py
@@ -61,10 +61,18 @@ def is_Graphics(x):
 
         sage: from sage.plot.graphics import is_Graphics
         sage: is_Graphics(1)
+        doctest:warning...
+        DeprecationWarning: The function is_Graphics is deprecated;
+        use 'isinstance(..., Graphics)' instead.
+        See https://github.com/sagemath/sage/issues/38184 for details.
         False
         sage: is_Graphics(disk((0.0, 0.0), 1, (0, pi/2)))                               # needs sage.symbolic
         True
     """
+    from sage.misc.superseded import deprecation
+    deprecation(38184,
+                "The function is_Graphics is deprecated; "
+                "use 'isinstance(..., Graphics)' instead.")
     return isinstance(x, Graphics)
 
 
diff --git a/src/sage/probability/random_variable.py b/src/sage/probability/random_variable.py
index a07af1220d6..1a779aba083 100644
--- a/src/sage/probability/random_variable.py
+++ b/src/sage/probability/random_variable.py
@@ -27,15 +27,31 @@
 ################################################################################
 
 def is_ProbabilitySpace(S):
+    from sage.misc.superseded import deprecation
+    deprecation(38184,
+                "The function is_ProbabilitySpace is deprecated; "
+                "use 'isinstance(..., ProbabilitySpace_generic)' instead.")
     return isinstance(S, ProbabilitySpace_generic)
 
 def is_DiscreteProbabilitySpace(S):
+    from sage.misc.superseded import deprecation
+    deprecation(38184,
+                "The function is_DiscreteProbabilitySpace is deprecated; "
+                "use 'isinstance(..., DiscreteProbabilitySpace)' instead.")
     return isinstance(S, DiscreteProbabilitySpace)
 
 def is_RandomVariable(X):
+    from sage.misc.superseded import deprecation
+    deprecation(38184,
+                "The function is_RandomVariable is deprecated; "
+                "use 'isinstance(..., RandomVariable_generic)' instead.")
     return isinstance(X, RandomVariable_generic)
 
 def is_DiscreteRandomVariable(X):
+    from sage.misc.superseded import deprecation
+    deprecation(38184,
+                "The function is_DiscreteRandomVariable is deprecated; "
+                "use 'isinstance(..., DiscreteRandomVariable)' instead.")
     return isinstance(X, DiscreteRandomVariable)
 
 ################################################################################
@@ -49,7 +65,7 @@ class RandomVariable_generic(Parent):
     A random variable.
     """
     def __init__(self, X, RR):
-        if not is_ProbabilitySpace(X):
+        if not isinstance(X, ProbabilitySpace_generic):
             raise TypeError("Argument X (= %s) must be a probability space" % X)
         Parent.__init__(self, X)
         self._codomain = RR
@@ -81,7 +97,7 @@ def __init__(self, X, f, codomain=None, check=False):
         - f -- a dictionary such that X[x] = value for x in X
           is the discrete function on X
         """
-        if not is_DiscreteProbabilitySpace(X):
+        if not isinstance(X, DiscreteProbabilitySpace):
             raise TypeError("Argument X (= %s) must be a discrete probability space" % X)
         if check:
             raise NotImplementedError("Not implemented")
diff --git a/src/sage/schemes/hyperelliptic_curves/monsky_washnitzer.py b/src/sage/schemes/hyperelliptic_curves/monsky_washnitzer.py
index 204030c1142..d9a9996d44e 100644
--- a/src/sage/schemes/hyperelliptic_curves/monsky_washnitzer.py
+++ b/src/sage/schemes/hyperelliptic_curves/monsky_washnitzer.py
@@ -56,7 +56,7 @@
 from sage.misc.repr import repr_lincomb
 from sage.modules.free_module_element import vector
 from sage.modules.free_module import FreeModule
-from sage.modules.free_module_element import is_FreeModuleElement
+from sage.modules.free_module_element import FreeModuleElement
 from sage.modules.module import Module
 from sage.rings.finite_rings.integer_mod_ring import IntegerModRing as Integers
 from sage.rings.integer import Integer
@@ -1894,7 +1894,7 @@ def __init__(self, parent, val=0, offset=0, check=True):
             return
         if isinstance(val, tuple):
             val, offset = val
-        if isinstance(val, list) and val and is_FreeModuleElement(val[0]):
+        if isinstance(val, list) and val and isinstance(val[0], FreeModuleElement):
             val = transpose_list(val)
         self._f = parent._poly_ring(val)
         if offset != 0: