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.

windyjonas

Get an overview of how active your users has been during a specified time period. This plugin will list all the users, 
the number of posts/pages they have created and when their latest post was created.
You can sort all the columns, filter by post type and search for a specific user name.
Note: This plugin uses the WP_List_Table, even though it is marked as @access private in WordPress core.
Plugin header image: 
<a href="https://www.flickr.com/photos/karen_roe/8655075297" rel="nofollow ugc"><img loading="lazy" decoding="async" src="https://live.staticflickr.com/8119/8655075297_212ce2c750_z.jpg" alt="The Big Egg Hunt 2013 - Covent Garden, London" width="640" height="427" /></a> 
Cropped to fit 
License: https://creativecommons.org/licenses/by/2.0/

User Activity

List number of posts per user. You can limit the search by date, post type and user name.

Better Author Metabox vs User Activity