In the forum options when you choose to change your avatar, it lets you pick your main character or upload your own image.
How do you change your main character so you can upload an image of it, without going through the arduous task of opening up a screenshot in MSPaint and making my own picture :]

To set your main character go to the My Characters page, locate the character you want to make your main and click "Set as Main" under the picture.

In the future, can get to the My Characters page from the main champions-online site via the dropdown next to My Account.

Aha, thanks :3

Thank you!

Honestly I hadn't even realized I could do this.

I don't know if it still works this way but at one pointt making a character and setting it as your main, then deleting that character would cause the avatar to cycle through your characters. It'll show a different character every time the avatar is loaded, even on different posts in the same thread.