Source: comicvine.gamespot.com

3. Hank Pym

Hank Pym was the first Ant-Man, first Giant-Man, first Goliath, first Yellowjacket, and second Wasp. He liked to change names and costumes.

The MCU’s Hank Pym was a Cold War operative who used his size-changing technology for covert operations. He eventually had to retire due to the strain the process put on his body. At that point, he became Scott Lang’s mentor. In the comics, Pym was a scientist who invented the Pym Particle and used it to go hang out with ants. He would also join his wife (we'll get to her in a minute) as a bit of a superhero – after he peer-pressured her into doing it.

After a year or so of this, Hank had an incredible breakthrough: If I can make myself small, could I make myself big? And that was when Giant-Man was born.

Hank also had a history of mental health issues that resulted in several psychotic breaks. The guy's just not well. He also built Ultron, so all blame is on him for that. Hank isn't great, you guys. I like him well enough, but it wasn’t until Scott came along that we had a shrinking superhero who wasn't a domestic abuser.

Hank is currently fused in a horrible way to Ultron, which gives him the opportunity to be a straight-up supervillain.