The “Mystery Man” avatar (floating left of the current paragraph) is the default WordPress avatar and it is used whenever a comment is added to your posts by a user who is not registered with Gravatar.
The result for your web-site is that you end up with a list of mixed comments some of which have a nice colorful user avatar attached to them and the rest left only with the grey, monotonous “Mystery Man”.
Now looking at the list of options provided by WordPress (go to WordPress Admin -> Settings -> Discussion and look at the bottom of the page), again there is nothing I would choose for my default WordPress avatar (floating on the right for your reference).
So the only choice you really have is to set-up your own. Quite a few people have asked me how to do this, so here you go.
How to add a Custom Default WordPress Avatar
To add a custom avatar, place the following code at the bottom of your functions.php file which is located in your theme folder.
Make sure you edit lines 6 and 7 according to your needs. For example, I named my custom default WordPress avatar file “new-avatar.png” and I have uploaded it to my images folder inside my theme. And then the description I gave for my new default avatar is “Genesis”.
From now on comments coming from users not registered with Gravatar will use this icon for your website.
That’s it. Let’s discuss it in the comments below. Did you follow the instructions alright? Did this work for you? Do you have any other way of doing this?