Flambo

Flambo is a small fire creature that first appears in the episode "Business Time." He was shown when Finn was using his head to light a flamethrower. Flambo appears to be completely fire, so he is probably from the Fire Kingdom.

Finn uses Flambo to light his flamethrower. He wears a special kind of glove when handling Flambo, and squeezes his torso; causing Flambo's head to get bigger/burn stronger. Finn then lets Flambo run away as he begins to melt icebergs; searching for junk to build a Gauntlet Dock.

Flambo returns in "The Chamber of Frozen Blades" acting as Finn and Jake's campfire while they are staking out the Ice Kingdom. Flambo apparently is their informant, having received a tip that Ice King was up to something suspicious. When Finn and Jake head off to investigate the castle, Finn tosses Flambo a piece of charcoal which he eats.

He is also seen helping Princess Bubblegum with a barbecue in the episode "The Real You," but causes a fire after Peppermint Butler stops watching the grill and argues with Chet.

Appearance
Flambo is completely made of fire and looks like a small animal; possibly a cat. He has stubby arms, legs, and a long, fiery tail. He runs on all fours but can also stand upright. When he eats coal, his flames become even larger.

Trivia

 * He has a Bronx accent.
 * He appears in "Legends of Ooo." You need him to light your tounges on fire, which he'll do in exchange for coal.
 * You can play as him in Flambo's Hot Mess