Sirius Pro

Simply exclude all author posts from indexing it in SERPs. This plugin allows you to noindex posts for certain authors without modifying the code and it works with most of the available themes. Just install and activate this plugin to add noindex and nofollow meta for all author posts.
Read more about this plugin on <a href="https://siriuspro.pl" rel="nofollow ugc">WordPress</a> blog.

Noindex Author

Simply exclude all author posts from indexing it in SERPs.

Kaspars

Metronet AS

Plugin adds a meta box to every post, page and custom post type where users with editor capabilities can promote other users (with author or contributor capabilities, by default) as editors of that post.
Plugin provides the following filters:
<ul>
<li><code>custom_editors_enable_roles</code> — Specify an array of user roles which should be allowed to be promoted as editors of specific posts and pages. The default is: <code>array( 'contributor', 'author' )</code>.</li>
</ul>
A plugin by <a href="http://metronet.no" rel="nofollow ugc">Metronet</a>.

Multiple Editors

Allow multiple editors and contributors per post or page. Also enable contributors and authors to upload files and add new pages by default.

Noindex Author vs Multiple Editors