Do any superheroes have an ill-tempered alter ego instead of a mild-mannered one?

I don't think anyone would refer to Logan (Wolverine) as mild-mannered.

I think Moon Knight and Deadpool count.

Alter ego is about conveying the nuance of ethics and moral disposition in a plainly obvious context for those that do not have the self awareness to discern such subtlety directly.

Rorschach

Guy Gardner is ill tempered all the time.