Simon Wheatley

A plugin providing template tags to list all active (or inactive) authors in the WordPress installation.
<pre><code><?php list_active_authors( 'days=30&include_protected_posts=0' ); ?> Will list all the authors active in the last 30 days, not counting password protected posts as "activity". Both parameters are optional.

<?php list_inactive_authors( 'days=30&include_protected_posts=0' ); ?> Will list all the authors NOT active in the last 30 days, counting password protected posts as "activity". Again, both parameters are optional.
</code></pre>
If “days” are not provided the tags default to the last 30 days. 
If “include_protected_posts” is not specified, the tags default to not including password protected posts.
The HTML output is fairly heavily classed, but if you need to adapt it you can. Create a directory in your theme called “view”, and a directory within that one called “author-listings”. Then copy the template files <code>view/author-listings/active-authors-list.php</code> and/or <code>view/author-listings/inactive-authors-list.php</code> from the plugin directory into your theme directory and amend as you need. If these files exist in these directories in your theme they will override the ones in the plugin directory. This is good because it means that when you update the plugin you can simply overwrite the old plugin directory as you haven’t changed any files in it. All hail <a href="http://urbangiraffe.com/" rel="nofollow ugc">John Godley</a> for the code which allows this magic to happen. Can hook into the <a href="https://wordpress.org/extend/plugins/user-photo/" rel="ugc">User Photo plugin</a> to display the author photos.
Plugin initially produced on behalf of <a href="http://www.puffbox.com" rel="nofollow ugc">Puffbox</a>.
Is this plugin lacking a feature you want? I’m happy to accept offers of feature sponsorship: <a href="http://www.simonwheatley.co.uk/contact-me/" rel="nofollow ugc">contact me</a> and we can discuss your ideas.
Any issues: <a href="http://www.simonwheatley.co.uk/contact-me/" rel="nofollow ugc">contact me</a>.

Author Listing

Allows listing of authors who are active or inactive within a defined recent period of time.

mattdu

This plugin uses the custom taxonomy features of WordPress to create “bylines” — essentially, tags representing authors who contributed to a post. The differentiating feature of this plugin is that it should not require any modifications to your theme files (assuming it is already displaying the post author).
This plugin would be useful for publishing situations where the majority of your content is from contributors who you don’t necessarily want to have access to your back-end. It still conveys the appearance that the authors are members of the site (it provides a built-in archive page for each Byline). If your theme displays tag descriptions, you could use the Byline description field to identify guests vs. “staff” writers or provide other author information.
You can see an example of this plugin at work at http://thedailycougar.com

Byline

The Byline plugin is simple and suitable for multi-author WordPress sites.

Best For Multi Author

Solves the co/multi-author problem without modifying the theme. Uses a custom taxonomy, "Byline," that replaces the Display Author.

Author Listing vs Byline