Source: armagideon-time.com

5. Mr. Atom

Aw, sweet! Mr. Atom!! I love Mr. Atom.

Despite sounding like the name of a public access television show host who teaches kids about science, that's not what he is. He is actually a giant murder robot.

Mr. Atom was built by Doctor Charles Langley in an experiment designed to create artificial life using nuclear energy. THIS IS A TERRIBLE IDEA!! WHAT THE HELL, MAN!! HOW DID YOU THINK THIS WAS GONNA TURN OUT?? The robot came to life and decided to take over the world. Oh, wow, who could have seen that coming?? OH, RIGHT, I DID! MY HAND IS RAISED.

Mr. Atom tried to conquer the earth numerous times, and was stopped over and over again by Captain Marvel. Y'know, for being a giant evil nuclear powered robot, Mr. Atom doesn't get used nearly as often as you would think. He should be up there with Brimstone and Chemo in the DC Universe giant monster category. But he just isn't used all that much. Sad.