Besides blatant canon ripoffs and OP characters, is there anything else we should stay away from when building our PCs?

What about demigods?
Super-Skrulls?
Characters from alternate timelines?

EDIT~

[quote=@DrewVonAwesome]
You realize if you're not going to post in X-Men I feel like I can't trust you for this right?
[/quote]
Understood