TOR, the Robot Criminal of Mars
Nemesis: Martian Manhunter
Other Major Foes: None
Appearances: One comic story.
Powers: Indestructible body, immortality, telepathy, telepathic immunity, superhuman strength/intellect, and ability to possess a host which bestowing its powers onto them. Vulnerable to fire and solar dust.
Bio: TOR was created by Martian scientists to be an eternal servant of extraordinary ability, but a programming error instead turned it into an unstoppable force for evil. Unable to effectively destroy the massive robot, Martians led by J'onn J'onzz instead lured TOR into a trap and stranded it on a dead world. TOR continued to plague the Martian Manhunter through its long range powers until it appeared to perish from environmental factors on its prison planet.
Win: The Headmaster (7-6); S'vor (8-4)
Lose: Despero (6-12); Mongul (5-9)
Nemesis: Champions of Angor
Other Major Foes: Justice League International
Appearances: 25+ comics, live action television, and animation.
Powers: Highly weaponized power suit with the usual ill-defined techno-enhancements.
Bio: The first Lord Havok was an other-dimensional super-villain whose team managed to kill themselves along with the world they were trying to conquer. He was reproduced through a robot duplicate, along with his fellow Extremists, and fought the JLI on several occasions. A third Lord Havok was formed when the Kilg%re merged with Maxwell Lord. The fourth and most recent version was from yet another dimension, a human born as Alexi Nikolai with severe birth defects. Nikolai's father sought his death as an embarrassment, but his mother loved and protected him until his scientific prowess gave him the means to become Lord Havok and conquer Earth-8.
Usually, this would be the other way around. Lord Havok is the Chromium Age villain modeled after Marvel's Doctor Doom but clearly less formidable who is mostly known through appearances in Justice League comics, but somehow isn't the one representing the Vile Menagerie today. Instead, TOR is the early Silver Age creation whose remarkable powers should easily triumph in this match. As a unit, the Extremists earned a rep for being severely dangerous thanks to slapping around Justice League Europe during its heavily muscled Bart Sears heyday in a story running parallel to Despero's high water mark against Adam Hughes' JLI. Unfortunately, the Extremists were hurt by their initial twist ending and some seriously half-assed revivals until they spent all the credibility a bunch of blatant analogues could muster. Lord Havok was sort of the face of the team, which led to him being repurposed as part of Max Lord's '90s heel turn, but nothing much ever came of that. The pre-Flashpoint version is probably the best and most dangerous of the bunch, in part because Liam Sharpe basically turned him into Death's Head II, but I still don't see him being enough to topple TOR.