antocara

Add a box with information about the author of each post after post written by that author. 
This box will display information in bio of each writer’s blog, a link to every post written by this author, avatar, and a series of icons link to author profile on social networks 
are known as Facebooks, Twitter, Google+ and icon for contact by email.
All these data the author of this post are collected from the profile of each author which have incorporated the necessary fields to fill. 
Author Info also has a widget in which appear a list of all components of the blog who have permission to write to the blog. This widget also displays the avatar of the author, 
his name with a link to a list of all posts written by him, the same icons to link to your profile on social networks and the number of written post. 
The box appears with the author’s information after each post is configurableboth in its background color, the color of the lettering and decorative border color of the table below.
Author info is configured for use in multi mode to be available in:
<ul>
<li>Spanish </li>
<li>English</li>
<li>Italian (gracias @cento)</li>
</ul>

CW Author Info

Add a box with information about the author of each post after post, include a widget in which appear a list of all components of the blog

David Biňovec

This plugin allows you to set users with <a href="https://codex.wordpress.org/Function_Reference/add_role" rel="nofollow ugc">custom role</a> as post, page or custom post type author.
In addition, this plugin allows you to set what <a href="https://codex.wordpress.org/Roles_and_Capabilities" rel="nofollow ugc">default roles</a> (even subscriber, contributor) shoud appear in author dropdown list.
Plugin developed with WP_DEBUG set true on WordPress 3.3.1 => No notices, warnings or errors

Custom roles for author

Allows to set users with custom role as post author.

CW Author Info vs Custom roles for author