On the right, you see the supervillain Mystique as played by Rebecca Romijn in the X-Men movies. On the left, you see a man cosplaying as her. And, I'll add, quite effectively. Both Romijn and the cosplayer have chosen to rely on minimal attire and body paint to convey their characters.
This is one of 20 pictures of men cosplaying as female characters rounded up by Pleated Jeans. Others include a hunky Misty, a bearded Sailor Moon, and a Catwoman(man) in a skin tight rubber suit.
(Images: unknown, Marvel Entertainment)