Ipstenu (Mika Epstein)

This plugin adds a new, sortable, column to the users lists, which shows the date and time they registered.
Primarily useful for single site (which doesn’t show this at all), on Multisite Networks it adds the user’s registration info for all individual sites.
<ul>
<li><a href="https://ko-fi.com/A236CEN/" rel="nofollow ugc">Donate</a></li>
<li><a href="http://halfelf.org/plugins/recently-registered/" rel="nofollow ugc">Plugin Site</a></li>
</ul>
<h3>Privacy Notes</h3>
This plugin does not track any additional data other than what WordPress natively collects upon registration. It just makes the data visble.

Recently Registered

Does what it says! It add new column in the user's dashboard!
You can also sort the users by registered date and that is very usefull

Useful. Works great, as I want

Add a sortable column to the users list to show registration date.

Pigrecolab

This plugin prevents the creation of new administrators, either by code, or by acting directly on the database. Ideal for locking possible backdoor hidden in code. 
BE CAREFULLY: DEACTIVATING THE PLUGIN YOU DON’T REMOVE THE BLOCK. YOU MUST USE THE PASSWORD IN SETTINGS / BLOCK NEW ADMIN AND DEACTIVATE THE BLOCK BEFORE DEACTIVATING THE PLUGIN
It provides:
<ol>
<li>A setting item to create a password to block o unblock a new administrator creation</li>
</ol>

Block New Admin

Works as advertised!!! Must be included in the core, sadly the core devs don't care or are clueless about security.

Excellent idea

A security plugin to block the creation of new administrators

Recently Registered vs Block New Admin