shooflydesign

This plugin can override the Authors metabox on the post add/edit screen, letting users who can edit other people’s posts, reassign a post to others user on the site.
This is especially useful in situations where you’ve created custom user roles that WordPress doesn’t recognize as Authors. If you want to allow your content editors and administrators to assign new or existing content to anyone, you’ll (hopefully) like this plugin very much indeed.
On WordPress 5.0, the metabox will appear below the main block editor (see screenshot). I will be supporting updates to the Status & Visibility box as soon as possible.
I’m not sure how far back this plugin will work, I’m saying it requires 3.5 or greater — it was originally developed using WordPress 4.1.
(Inspired by <a href="https://core.trac.wordpress.org/ticket/18645" rel="nofollow ugc">this trac ticket</a>)

Better Author Metabox

Lets you safely override the built-in Author metabox with one that includes more users.

Elliott Richmond

Sometimes handing your site over to clients or when you run a site with multiple users if can be a pain to explain how your 
users can create their own profile picture for comments or any other custom functionality that uses the get_avatar() function.
Before they would have to create a global Gravatar account which is fine if that’s what you want however, with this plugin there 
is no need to rely on your users having a Gravatar account.
This plugin will allow the users on your WordPress site to upload their own Profile Picture through the Media Library either by Uploading a new file or choosing one from the Media Library.

Tismy User Profile Upload

Upload your own user profile picture rather than falling back to the default or having your users create a Gravatar account.

Better Author Metabox vs Tismy User Profile Upload