Mammoth is one of the founding members of the Fearsome Five, and became an enemy of the Teen Titans, Superman, and the Outsiders. He is highly devoted to his sister Selinda (a.k.a. Shimmer), also a founding member of the Fearsome Five. A towering hulk of a man with immense physical strength and durability, Mammoth is intellectually and emotionally underdeveloped (so much so that he was once tricked into surrendering to a Superman whose powers had recently been lost thanks to Lex Luthor's use of Mister Mxyzptlk's red kryptonite thanks to Superman simply faking confidence that he could defeat Mammoth), and he lacks skill as a hand-to-hand combatant.