Bart Kuijper

When displaying a post or comment with avatars enabled, WordPress will always check for the existence of a Gravatar. (Note: even the default avatars ‘mystery person’ and ‘blank’ are in fact Gravatars served from gravatar.com.) WordPress does this by sending an MD5 hash of every displayed post or comment author’s email address to gravatar.com. Even with many plugins that introduce locally stored default or user avatars, this check still happens. On top of that, some themes or plugins force (Gr)avatars to load even if the display of avatars is disabled completely in WordPress’ settings. If for whatever reason you do not wish for Gravatar to receive these requests (which some people have voiced GDPR concerns about), this plugin is for you.
The way it works is every time WordPress attempts to display an avatar, this plugin first checks if the image is about to be retrieved from gravatar.com. If it is, the URL is changed to the locally stored ‘mystery person’ image (included with this plugin). If the avatar has any other source, this plugin doesn’t interfere.
Gravatars are also removed from the Discussion page in Settings and replaced with the locally stored ‘mystery person’ image. Again, any non-Gravatar images are left alone.
Upon activation of this plugin, if a Gravatar is selected as the default avatar, that setting is changed to the locally stored ‘mystery person’ image. If any non-Gravatar avatar is selected, that setting isn’t changed.
Upon deactivation of this plugin, if the locally stored ‘mystery person’ image is selected as the default avatar, that setting is changed to the Gravatar logo. If any non-Gravatar avatar is selected, that setting isn’t changed.

Redirect Gravatar requests

All requests to load an avatar from gravatar.com are redirected to a local image, preventing Gravatar from potentially gathering data about your site  …

Dougal Campbell

This plugin allows you to automatically add Gravatars for commenters to your 
theme, if your theme does not already support them.
According to the Gravatar.com website, Gravatars are Globally Recognized 
Avatars, or an “avatar image that follows you from weblog to weblog 
appearing beside your name when you comment on gravatar enabled sites.” 
You register with the Gravatar server, and upload an image which you will 
use as your avatar. The gravatar image is keyed to your email address, so 
that it is unique to you.
This plugin will display gravatars for the people who comment on your posts. 
You do not need to modify any of your template files — just activate the 
plugin, and it will add gravatars to your comments template automatically.
<h3>Credits</h3>
Based on a code snippet from Matt Mullenweg: 
 http://photomatt.net/2007/10/20/gravatar-enabled/ 
 http://pastebin.ca/743979
Props to David Potter for pointing out that Gravatar normalizes email 
addresses to lowercase before hashing with MD5: 
 http://dpotter.net/Technical/index.php/2007/10/22/integrating-gravatar-support/

Easy Gravatars

nice

Add Gravatars to your comments without modifying any template files. Just activate, and you're done!

Redirect Gravatar requests vs Easy Gravatars