I feel like I have a laundry list of these, but I'm having a little trouble remembering them all. Usually I reserve my thoughts about dramatic revamping (of costume, never really thematics) for like, the Z-List.
But one that stands out to me is "The Eraser", from the sixties "New Yellow Oval" period. The guy's name is Lenny Fiasco - fantastic name - and he was like, what, Bruce Wayne's roommate or something? He has a major connection as a friend of Bruce's from youth, but he goes by The Eraser and in full ridiculous silly mode dresses like a yellow No. 2 pencil with an eraser for a head/mask. That's daffy as hell. But the notion that an old close friend of Bruce's, is a dapper, showy consulting criminal who "erases" the evidence for other criminals is gorgeous, and the notion that he might've educated himself at the same university as Bruce in criminal investigation/crime scene studies, but uses that knowledge-base to make life almost impossible for the dark knight detective is just utterly great.
I'd pay homage to the silly pencil costume by having him have a special "crime scene erasing" hazmat-type costume, that's yellow, and having him wear a lot of sleek gold suits and stuff. He'd be so rich, too, that the only reason Batman could solve the cases is because of the happenstance/luck that Bruce Wayne just happens to know the guy personally. Batman can't solve the case, without Bruce Wayne, because Lenny sees Bruce as a dilettante who wasted his criminology education by becoming a rich playboy and charity fundraiser.
I mean, he'd be the B-villain probably, in an arc about the criminal who was criming the big crimes and using Eraser to get away with them, whether that be a gangster or major villain or something. But a total thorn in Batman's side.