The family name Magnuson is named after Magnus himself. The name comes from Norse origins meaning literally "house of power".
The name Magnus means "Great" in Latin, because of his large body mass, incredibly strong strength and strong earthquake voice; the name is technically a royal name aswell and in Old Norse originally meant "house of might/power" which is a perfect meaning to due his personality and physical feats.
Though his appearance is intimidating Magnus has shown signs of cowardness in several episodes, such as being frightened by "The Dark One " in "Stand and Delivery" and his own wife.
It is revealed in "Garage Banned" that he and Kick's Dad were once in a band together dubbed the "Yeah Dad's". He plays an electric guitar which the attire is similar to an axe.