For the black & white movie days... Barbara Stanwyck. I get that in Double Indemnity she's supposed to be an evil bitch, but even in movies where she's supposed to be the one you're rooting for...she's terrible. And in one movie I saw with her I didn't even realise it was her at first and I was still like, 'This person is terrible.' and then I realised it was her.
For the modern day - being somebody born in the 80s that grew up in the 90s... Di Caprio. Even when I was a kid I was like, 'There's something off with him and I don't know it is, but there's something off....' and everybody else is going on about how amazing he is. Now at least we know that he's a predatory creep.
Classics like Bugs Bunny and Animaniacs were always good. Doug. Pepper Anne.
Ones that most people have forgotten or didn't know because they weren't exposed to Canadian shows as a kid:
Science Court was on ABC's One Saturday Morning and I loved it. Technically a Sunday morning one, but The Smoggies for the Canadian people here that are of a certain age! The Raccoons (another Canadian one)