The usual mascots would be wolves, powerpufff girls, manga, ponies, or sonic characters.
Instead of drawing themself in creations, artists would usually draw their mascots. They wouldn't use mascots if they're creating pictures of disney characters or, ofcourse, a self-portrait. Also mostly they put mascots on their logos.
Creating a mascot
To create a mascot you first pick the style you are most used to. If you aren't good at the certain style, in all of those creations with your mascot in it, it would take forever to make them good. And a lot of pictures iinclude your mascot. Then you would think of the personality and make them look like it. For example, if I do someone joyful, I usually think of giving him/her light colors. Give it a name and a bio and you're finished!
Hope this helped 'cause this is my first ever page on wikia