|Vehicles and/or Gadgets||None|
|Residence||Boom Boom Mountain|
Mountain Man is a living mountain who appears in "Memories of Boom Boom Mountain." He hates when the Marauders roughhouse - the violence makes him sad and their fantastic bodies aggravate him. Being a stationary mountain, he is unable to look away. He seems very fragile and caring of both people's and animal's health and well-being. He cries boulders out of his eyes, often causing avalanches. He was the first character on Adventure Time to say "math" as a profane word.
He is located next to Mountain 2 who enjoys staring at his beautiful back, which poses a problem. Mountain Man wants to look away so that he won't see the Marauders roughhouse, but the female mountain enjoys staring at the male mountain's back.
- In the series, he is voiced by Matt L. Jones. In the game, he is mute.
- He is sometimes erroneously referred to as "Boom Boom Mountain" due to the episode's title, but the dialogue and character design sheet call him "Mountain Man."
- Mountain Man is one of the first to be both a character and a location.