[quote=@ErsatzEmperor]
Black Canary?
[/quote]

I was going to ask which one, but since the second one is the only one with powers I'll save myself asking that question. Originally during the Silver Age, Dinah's powers were due to a curse by a Wizard but she was retconned to having a Meta-Gene so I suppose you could argue she'd be a mutant.

[quote=@Divine Darkness]
[url=https://en.wikipedia.org/wiki/Mutant_(fictional)#DC_Comics]Wiki[/url] gives a few examples of a DC characters that could possibly be considered "mutants". Killer Croc for instance?
[/quote]

Yeah I'd say Croc is probably a mutant.