Doctor Octopus

Doctor Octopus is a super villain and member of the Sinister Six

Involvement in Story
Doc Ock formed the first iteration of the Sinister Six, and has been a part of most iterations since then.

He teamed up with the Joker to launch missiles to Gotham City, Metropolis, and New York, but Joker betrayed Ock. Fortunately, this plot was foiled by Shazam, The Question, Batman, and Doctor Strange.