Massive is a very large criminal who can control gravity and has a tough body structure that even lasers cannot penetrate. He commits robberies simply to make himself rich and seemingly has a compulsion for this behavior. He is also not shy about this, telling everyone his name right before he robs them.
The only limit to his powers is a kind of conservation of energy, meaning making something heavier means making something else lighter, and vice versa, although this isn't always demonstrated.