The Best Adventure Time Episodes To Watch During Halloween

"It Came from the Nightosphere" begins with Finn and Marceline having a jam session. After Marceline sings a moody song about her dad stealing her fries, Finn is eager to help father and daughter reconcile. One quick and creepy ritual later, Hunson Abadeer, Lord of the Nightosphere and Marceline's dad, arrives.

Ever the bad guy, Hunson immediately begins a terrifying, soul-sucking tour across Ooo. But before he leaves, he takes Marceline's bass, which we learn is a family axe (like, a literal axe) that Marcy has refashioned into an instrument. Finn and Marceline set off to stop Hunson, though Marceline is mostly interested in getting her bass back. 

"It Came from the Nightosphere" does a perfect job of introducing Hunson Abadeer, who is equally invested in evil and being a good dad, even though he has a hard time with the latter gig. The episode also offers a number of nicely scary moments, a surprisingly catchy song about sucking ants' souls, Marceline's iconic french fry lament, and a genuinely sweet resolution.