Firefly is pyromaniac supervillain. He made a tiny cameo in the episode "So You Need a Crew?" when Poison Ivy recounted Queen of Fables' backstory. His weapon, a plasma flamethrower is shown to be a plot point for Harley Quinn to acquire it to break through Mister Freeze's ice fortress. When the city of Gotham fell after the events of "The Final Joke", Doctor Trap looted all the villain's lairs and collected many items at the Gotham Natural History Museum, including Firefly's flamethrower. During "Catwoman" Harley managed to get the flamethrower from Doctor Trap which she used to break into Mister Freeze's fortress in "Thawing Hearts".