rockgod100

This plugin creates an area for site admins to jot down post ideas or assign post topics to content authors. Additionally, authors can be given due dates and suggested post types (article, video, etc).
Admins can also e-mail authors directly through the interface using an extension of the wp_mail() function.

Topic Manger

A quick way to remember post topics for single or multi-author blogs

flocsy

Authors Widget shows the list or cloud of the authors, with the number of posts, link to RSS feed next to their name, avatar. It is useful in a multi-author blog, where you want to have the list in the sidemenu. 
The widget can also display an “Author Cloud” if <a href="https://wordpress.org/extend/plugins/seo-tag-cloud/" rel="ugc">SEO Tag Cloud plugin</a> is installed.

Authors Widget

Authors Widget shows the list or cloud of the authors in the sidemenu.

Topic Manger vs Authors Widget