The Hulk: Caught in a gamma bomb test, Dr. Bruce Banner found that the radiation had affected him on a genetic level, and that moments of stress or anger transformed him into the monstrous Hulk. While he fought alongside the Avengers early on, the team has had to battle their savage friend on more than one occasion.

Thor: Known on Earth as the fabled Norse God of Thunder, Thor is in actuality a member of the Asgardian race, who live on another plane of existence from Earth. With the help of an enchanted hammer given him by his father, Thor can fly and control the weather, and his love of Midgard has led him to protect it as an Avenger.