Glad to see more interest! Yes canons are welcomed, and original characters are encouraged. So either one is fine (or both).

[@Jensoman] For people who aren't able to post too regularly there is the option of being a villain character. You certainly don't have to take this route, but it's recommended. You're more than welcome to play a canon villain or make an OC. Keep in mind that you can still opt to play a hero.