|Relatives||Big Monster, Giant Monster|
|Introduced In||Finn's Missing|
Massive Monster is a character who was first seen in Finn's Missing. He was one of the monster where Jake, Lady Rainicorn and BMO came across and fought. He is the biggest one of his brothers.
Massive Monster is the biggest of them all. He only has appeared in his copy form in which he resembles Finn. His arm has merged with a fake Demon Sword and he has a third eye.
Massive Monster has immense strenght and can copy the abilities of his opponents if he touches them or if he gets touched by them.