Thanos!
AKA: The Living Titan. The Mad Titan. Purple Puss. God.
First Appearance: Iron Man 55
What's His Problem? Thanos, one of the Eternals of Titan (not to be confused with the Eternals of other planets or the Externals of the X-Men), is the lover of Death. Not that he's especially fond of exterminating life forms -- well, okay, he is, but that's entirely incidental -- Thanos is the actual chosen mate of Death herself. Death, as you can imagine, is a fickle mistress, but Thanos can't seem to stay away from her, whatever state his own current vital signs are in. He has twice brought the Universe to the edge of annihilation to achieve her favor, and even obtained the Infinity Gems to reign by her side as her equal. He has ever miscalculated Death's heart, however, and has yet to win a single word of approval from her.
Died in: Yep, the lover of Death can die, and did, in Captain Marvel 33 and Marvel Two-In-One Annual 2. That didn't stop him from causing havoc (and even saving the day once or twice) during various Infinity cross-overs.
Powers: Considering Thanos is but a mortal, he has astonishing might. Thanos' mutant strength far outstrips that of his fellow Eternals; not satisfied with being the strongest of the Titans, he bionically augmented himself, turning himself into a physical powerhouse that can withstand a brutal pounding by various Norse gods. His mutancy doesn't stop with mere strength; he is also a natural cosmic energy conduit. He has occasionally held almost incalculable external power, once nearly absorbing the Cosmic Cube and at another time gathering together the Infinity Gems which permitted him to become ... well, God.
Favorite Quote: "How can I possibly resist such a challenge...? I can't. Intellectual curiosity will yet be the downfall of me." (Warlock and the Infinity Watch 19. An articulate and even amusing guy is Thanos; admire his wit as he's crushing your skull).
Heroes He Keeps Running Into: Thanos had a major tussle or two with Captain Marvel before Mar-Vell died of cancer; he has had relatively minor ones with Iron Man, Ka-Zar, the Silver Surfer, Thor and even all-powerful Odin. His chief adversary-turned-relunctant-ally is Adam Warlock, someone who has escaped Death once or twice himself. Often caught up in Thanos' far-reaching schemes are the Avengers and members of the Fantastic Four, especially the Thing, although they all tend to be peripheral foes at best. The main event ever hinges on Warlock, who as a unique being outside the control of the Universal Powers-That-Be (a select lot that includes the likes of Galactus, the Celestials, Lord Chaos and Master Order, and even Eternity) is often the only possible chance the Universe has to survive Thanos' latest grab for power.
People Who Think He's Not So Bad: Probably the only person who ever thinks kindly of Thanos is Gamora, who was raised by him to be the most feared woman in the galaxy; she tolerates him pretty well despite once being killed by him. Thanos' other Infinity Watch teammates don't trust him. His own family, which include the sometimes Avenger Starfox, avoid him like the plague upon the Universe that he is. Warlock has repeatedly been forced into alliances with Thanos, and even appointed him guardian of the Reality Gem, but it isn't because Adam has any illusions about Thanos' ultimate goal. And Death herself has kept a wary eye on Thanos since he tried to usurp her power and demanded to be treated as her equal.
Most Despicable Act: I'd have to give the nod to Thanos' attempt to win the favor of Death by striving to extinguish the stars, which of course would have resulted in exterminating the entire universe. Avengers' web-master Van Plexico, however, thinks the nastiest thing Thanos ever did was during the Infinity Gauntlet series, when as a homage to his lover (and as a demonstration of his own divine power) the Titan kept his alleged granddaughter Nebula in a state approaching death, but would not actually permit her to die. That, I agree, is very nasty.