pejorative language - Word for someone who is jovial, but malicious?

Just googling synonyms gives a lot of synonyms, and classic mythology is a good source too. There are trickster gods like Puck or Loki or Pan. Or satyrs in general, which also has similarities to 'satire'.

But I would try to look for names that can have double meanings. For (bad) example, "the gagger". When he is first described in the game, people likely think of choking, but then they discover he isn't. This in and of itself is a gag and a mindtrick. It's similar to how the Joker is both about jokes, and being a wildcard.

The kipper, which is a fish, specifically red herring.
The goose, and you're on a wild-goose chase.
The mocker; both one who mocks others, but also one that creates mock-events to distract.
The dummy, a smart man leaving behind false evidences.

Though all of these are more grouped around deception than malvolent behaviour, I hope it gives a different perspective on things.