Odd Mushroom is a troll found in the troll town of Weiss, who is an inventor and also Mother's advisor. Unlike most trolls, Odd Mushroom is extremely intelligent and speaks perfect English, like the Troll father, troll mother and troll child. He values skills over combat, having more affection for Mother's daughter Snowflake due to being his pupil and her quick learning capabilities.
During Making Friends with My Arm, he is mortally wounded by Mother after discovering he was tricked into believing the Wise Old Man was dead. He succumbs to his wounds in prison shortly after instructing the player to find his notes.