diff --git a/Commands.md b/Commands.md
index 26876b460..dfcbd7251 100644
--- a/Commands.md
+++ b/Commands.md
@@ -9,6 +9,7 @@
  - [`git chore`](#git-featurerefactorbugchore)
  - [`git clear`](#git-clear)
  - [`git clear-soft`](#git-clear-soft)
+ - [`git coauthor`](#git-coauthor)
  - [`git commits-since`](#git-commits-since)
  - [`git contrib`](#git-contrib)
  - [`git count`](#git-count)
@@ -347,6 +348,30 @@ Straight from the shell!
 git (master)> quit
 ```
 
+## git coauthor
+
+Add a co-author to the last commit
+
+```bash
+$ git coauthor user user@email.com
+
+[master b62ceae] Add documentation files
+ Date: Sat Aug 17 17:33:53 2019 -0500
+ 2 files changed, 145 insertions(+), 0 deletions(-)
+ create mode 100644 README.md
+ create mode 100644 CONTRIBUTING.md
+ 
+ $ git log -1
+ 
+commit b62ceae2685e6ece071f3c3754e9b77fd0a35c88 (HEAD -> master)
+Author: user person <userperson@email.com>
+Date:   Sat Aug 17 17:33:53 2019 -0500
+
+    Add documentation files
+
+    Co-authored-by: user <user@email.com>
+```
+
 ## git commits-since
 
 List commits since `date` (defaults to "last week"):
diff --git a/bin/git-coauthor b/bin/git-coauthor
new file mode 100755
index 000000000..522f2db80
--- /dev/null
+++ b/bin/git-coauthor
@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+
+set -e -o pipefail
+
+coauthor=$1
+email=$2
+
+test -z "$coauthor" && echo "co-author required." 1>&2 && exit 1
+test -z "$email" && echo "co-author email required." 1>&2 && exit 1
+
+old_message="$(git log --format=%B -n1)"
+if [[ $old_message == *"Co-authored-by:"* ]]; then
+  git commit --amend -m "$old_message
+Co-authored-by: $coauthor <$email>"
+else
+  git commit --amend -m "$old_message" -m "Co-authored-by: $coauthor <$email>"
+fi
diff --git a/etc/git-extras-completion.zsh b/etc/git-extras-completion.zsh
index 713121050..0552eca42 100644
--- a/etc/git-extras-completion.zsh
+++ b/etc/git-extras-completion.zsh
@@ -196,6 +196,11 @@ _git-chore() {
         '(--remote -r)'{--remote,-r}'[setup remote tracking branch]'
 }
 
+_git-coauthor() {
+    _arguments \
+        ':co-author[co-author to add]' \
+        ':co-author-email[email address of co-author to add]'
+}
 
 _git-contrib() {
     _arguments \
@@ -441,6 +446,7 @@ zstyle ':completion:*:*:git:*' user-commands $existing_user_commands \
     chore:'create chore branch' \
     clear-soft:'soft clean up a repository' \
     clear:'rigorously clean up a repository' \
+    coauthor: 'add a co-author to the last commit' \
     commits-since:'show commit logs since some date' \
     contrib:'show user contributions' \
     count:'show commit count' \
diff --git a/man/git-coauthor.1 b/man/git-coauthor.1
new file mode 100644
index 000000000..9e8acf424
--- /dev/null
+++ b/man/git-coauthor.1
@@ -0,0 +1,42 @@
+.\" generated with Ronn/v0.7.3
+.\" http://github.com/rtomayko/ronn/tree/0.7.3
+.
+.TH "GIT\-COAUTHOR" "1" "August 2019" "" "Git Extras"
+.
+.SH "NAME"
+\fBgit\-coauthor\fR \- Add a co\-author to the last commit
+.
+.SH "SYNOPSIS"
+\fBgit\-coauthor\fR <co\-author> <co\-author\-email>
+.
+.SH "DESCRIPTION"
+Add a co\-author to the last commit
+.
+.SH "OPTIONS"
+<co\-author>
+.
+.P
+The username of the co\-author you want to add\.
+.
+.P
+<co\-author\-email>
+.
+.P
+The email address of the author you want to add\.
+.
+.SH "EXAMPLES"
+.
+.nf
+
+$ git coauthor user user@email\.com
+.
+.fi
+.
+.SH "AUTHOR"
+Written by Jacob Herrington \fIjacobherringtondeveloper@gmail\.com\fR
+.
+.SH "REPORTING BUGS"
+<\fIhttps://github\.com/tj/git\-extras/issues\fR>
+.
+.SH "SEE ALSO"
+<\fIhttps://github\.com/tj/git\-extras\fR>
diff --git a/man/git-coauthor.html b/man/git-coauthor.html
new file mode 100644
index 000000000..f7a7ac71e
--- /dev/null
+++ b/man/git-coauthor.html
@@ -0,0 +1,121 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <meta http-equiv='content-type' value='text/html;charset=utf8'>
+  <meta name='generator' value='Ronn/v0.7.3 (http://github.com/rtomayko/ronn/tree/0.7.3)'>
+  <title>git-coauthor(1) - Add a co-author to the last commit</title>
+  <style type='text/css' media='all'>
+  /* style: man */
+  body#manpage {margin:0}
+  .mp {max-width:100ex;padding:0 9ex 1ex 4ex}
+  .mp p,.mp pre,.mp ul,.mp ol,.mp dl {margin:0 0 20px 0}
+  .mp h2 {margin:10px 0 0 0}
+  .mp > p,.mp > pre,.mp > ul,.mp > ol,.mp > dl {margin-left:8ex}
+  .mp h3 {margin:0 0 0 4ex}
+  .mp dt {margin:0;clear:left}
+  .mp dt.flush {float:left;width:8ex}
+  .mp dd {margin:0 0 0 9ex}
+  .mp h1,.mp h2,.mp h3,.mp h4 {clear:left}
+  .mp pre {margin-bottom:20px}
+  .mp pre+h2,.mp pre+h3 {margin-top:22px}
+  .mp h2+pre,.mp h3+pre {margin-top:5px}
+  .mp img {display:block;margin:auto}
+  .mp h1.man-title {display:none}
+  .mp,.mp code,.mp pre,.mp tt,.mp kbd,.mp samp,.mp h3,.mp h4 {font-family:monospace;font-size:14px;line-height:1.42857142857143}
+  .mp h2 {font-size:16px;line-height:1.25}
+  .mp h1 {font-size:20px;line-height:2}
+  .mp {text-align:justify;background:#fff}
+  .mp,.mp code,.mp pre,.mp pre code,.mp tt,.mp kbd,.mp samp {color:#131211}
+  .mp h1,.mp h2,.mp h3,.mp h4 {color:#030201}
+  .mp u {text-decoration:underline}
+  .mp code,.mp strong,.mp b {font-weight:bold;color:#131211}
+  .mp em,.mp var {font-style:italic;color:#232221;text-decoration:none}
+  .mp a,.mp a:link,.mp a:hover,.mp a code,.mp a pre,.mp a tt,.mp a kbd,.mp a samp {color:#0000ff}
+  .mp b.man-ref {font-weight:normal;color:#434241}
+  .mp pre {padding:0 4ex}
+  .mp pre code {font-weight:normal;color:#434241}
+  .mp h2+pre,h3+pre {padding-left:0}
+  ol.man-decor,ol.man-decor li {margin:3px 0 10px 0;padding:0;float:left;width:33%;list-style-type:none;text-transform:uppercase;color:#999;letter-spacing:1px}
+  ol.man-decor {width:100%}
+  ol.man-decor li.tl {text-align:left}
+  ol.man-decor li.tc {text-align:center;letter-spacing:4px}
+  ol.man-decor li.tr {text-align:right;float:right}
+  </style>
+</head>
+<!--
+  The following styles are deprecated and will be removed at some point:
+  div#man, div#man ol.man, div#man ol.head, div#man ol.man.
+
+  The .man-page, .man-decor, .man-head, .man-foot, .man-title, and
+  .man-navigation should be used instead.
+-->
+<body id='manpage'>
+  <div class='mp' id='man'>
+
+  <div class='man-navigation' style='display:none'>
+    <a href="#NAME">NAME</a>
+    <a href="#SYNOPSIS">SYNOPSIS</a>
+    <a href="#DESCRIPTION">DESCRIPTION</a>
+    <a href="#OPTIONS">OPTIONS</a>
+    <a href="#EXAMPLES">EXAMPLES</a>
+    <a href="#AUTHOR">AUTHOR</a>
+    <a href="#REPORTING-BUGS">REPORTING BUGS</a>
+    <a href="#SEE-ALSO">SEE ALSO</a>
+  </div>
+
+  <ol class='man-decor man-head man head'>
+    <li class='tl'>git-coauthor(1)</li>
+    <li class='tc'>Git Extras</li>
+    <li class='tr'>git-coauthor(1)</li>
+  </ol>
+
+  <h2 id="NAME">NAME</h2>
+<p class="man-name">
+  <code>git-coauthor</code> - <span class="man-whatis">Add a co-author to the last commit</span>
+</p>
+
+<h2 id="SYNOPSIS">SYNOPSIS</h2>
+
+<p><code>git-coauthor</code> &lt;co-author&gt; &lt;co-author-email&gt;</p>
+
+<h2 id="DESCRIPTION">DESCRIPTION</h2>
+
+<p>  Add a co-author to the last commit</p>
+
+<h2 id="OPTIONS">OPTIONS</h2>
+
+<p>  &lt;co-author&gt;</p>
+
+<p>  The username of the co-author you want to add.</p>
+
+<p>  &lt;co-author-email&gt;</p>
+
+<p>  The email address of the author you want to add.</p>
+
+<h2 id="EXAMPLES">EXAMPLES</h2>
+
+<pre><code>$ git coauthor user user@email.com
+</code></pre>
+
+<h2 id="AUTHOR">AUTHOR</h2>
+
+<p>Written by Jacob Herrington <a href="&#109;&#97;&#105;&#108;&#116;&#111;&#58;&#106;&#97;&#99;&#x6f;&#98;&#104;&#x65;&#x72;&#114;&#105;&#110;&#x67;&#116;&#x6f;&#x6e;&#x64;&#x65;&#x76;&#x65;&#x6c;&#111;&#112;&#x65;&#x72;&#64;&#103;&#109;&#x61;&#105;&#108;&#x2e;&#99;&#111;&#109;" data-bare-link="true">&#x6a;&#97;&#99;&#111;&#98;&#104;&#101;&#114;&#114;&#105;&#x6e;&#x67;&#x74;&#111;&#110;&#100;&#x65;&#118;&#101;&#108;&#111;&#x70;&#101;&#114;&#64;&#103;&#109;&#x61;&#105;&#x6c;&#x2e;&#99;&#x6f;&#x6d;</a></p>
+
+<h2 id="REPORTING-BUGS">REPORTING BUGS</h2>
+
+<p>&lt;<a href="https://github.com/tj/git-extras/issues" data-bare-link="true">https://github.com/tj/git-extras/issues</a>&gt;</p>
+
+<h2 id="SEE-ALSO">SEE ALSO</h2>
+
+<p>&lt;<a href="https://github.com/tj/git-extras" data-bare-link="true">https://github.com/tj/git-extras</a>&gt;</p>
+
+
+  <ol class='man-decor man-foot man foot'>
+    <li class='tl'></li>
+    <li class='tc'>August 2019</li>
+    <li class='tr'>git-coauthor(1)</li>
+  </ol>
+
+  </div>
+</body>
+</html>
diff --git a/man/git-coauthor.md b/man/git-coauthor.md
new file mode 100644
index 000000000..15d8181ae
--- /dev/null
+++ b/man/git-coauthor.md
@@ -0,0 +1,36 @@
+git-coauthor(1) -- Add a co-author to the last commit
+================================
+
+## SYNOPSIS
+
+`git-coauthor` &lt;co-author&gt; &lt;co-author-email&gt;
+
+## DESCRIPTION
+
+  Add a co-author to the last commit
+
+## OPTIONS
+
+  &lt;co-author&gt;
+
+  The username of the co-author you want to add.
+
+  &lt;co-author-email&gt;
+  
+  The email address of the author you want to add.
+
+## EXAMPLES
+
+    $ git coauthor user user@email.com
+
+## AUTHOR
+
+Written by Jacob Herrington <jacobherringtondeveloper@gmail.com>
+
+## REPORTING BUGS
+
+&lt;<https://github.com/tj/git-extras/issues>&gt;
+
+## SEE ALSO
+
+&lt;<https://github.com/tj/git-extras>&gt;
diff --git a/man/git-extras.md b/man/git-extras.md
index ab09ec63b..788653dfc 100644
--- a/man/git-extras.md
+++ b/man/git-extras.md
@@ -31,6 +31,7 @@ git-extras(1) -- Awesome GIT utilities
    - **git-chore(1)** Create chore branch
    - **git-clear-soft(1)** Soft clean up a repository
    - **git-clear(1)** Rigorously clean up a repository
+   - **git-coauthor(1)** Add a co-author to the last commit
    - **git-commits-since(1)** Show commit logs since some date
    - **git-contrib(1)** Show user's contributions
    - **git-count(1)** Show commit count
diff --git a/man/index.txt b/man/index.txt
index e90c14c02..f4ab5c021 100644
--- a/man/index.txt
+++ b/man/index.txt
@@ -9,6 +9,7 @@ git-changelog(1) git-changelog
 git-chore(1) git-chore
 git-clear-soft(1) git-clear-soft
 git-clear(1) git-clear
+git-coauthor(1) git-coauthor
 git-commits-since(1) git-commits-since
 git-contrib(1) git-contrib
 git-count(1) git-count