Doctor Thaddeus Bodog Sivana, Sr. is Captain Marvel's arch-nemesis. A brilliant evil mastermind, he is arguably the archetype for the "mad scientist". Sivana was the first to figure out Captain Marvel's identity, and has been a constant pest to the Big Red Cheese (as he prefers to call the Captain). He has been associated with the Monster Society of Evil and the Secret Society. He also had a son, Thaddeus Sivana, Jr., and a daughter, Georgia Sivana, who both resemble him.
Doctor Thaddeus Sivana is a genius inventor and scientist; who had been summoned by the wizard Shazam as a child, but was not chosen as his champion, leading Sivana to spend his entire life trying to unlock the secrets of magic. After discovering Billy Batson was the wizard's new champion, Sivana attempted to steal his powers with help from the Seven Deadly Enemies of Man, but was ultimately defeated and imprisoned in his pursuit.
- Mark Strong, who played Dr. Sivana in Shazam!, also played Sinestro in 2011 movie, Green Lantern.