Joker (Persona 5)

Joker is a phantom thief and a vigilante.

Stupid Alliance Story
He was found trapped on Murder Inc World and was freed by the Stupid Alliance, aiding them against Daddy Dearest and the Masterminds of Evil.

Stupid Alliance 2 Story
Joker doesn't contribute much to the story, being an "exclusive" character.

Stupid Alliance 3 Story
Joker is playable on the "Curse of the Vampire" expansion.