Wait. That last bit is confusing. What, exactly, is his motivation?
Thanos’s raison d’être is, indeed, one of the weirdest in comics history. Within the Marvel universe, there are various supernatural beings that are living embodiments of abstract concepts like eternity, infinity, and death. They’re even more powerful than gods, and mainly show up in stories set in outer space. One such supernatural being is Death, who takes the form of a woman in a purple robe (sometimes she’s beautiful, and sometimes she’s a skeleton). Thanos is in love with Death and, more often than not, enacts his genocidal schemes as a way to impress her with his killing ability. Riches and world domination mean very little to him: He dreams bigger than any other major Marvel villain.

What’s Thanos’s backstory, and why does he look like a grumpy purple hippopotamus?
He’s a member of a race of genetically modified humans called the Eternals (their ancestors were plucked from prehistoric Earth by godlike beings called the Celestials, then given superpowers). They’re scattered throughout the galaxy, and the colony Thanos was born into resides on Titan, one of Saturn’s moons (these particular Eternals are sometimes called Titans, and Thanos is known as the Mad Titan). The Eternals have various (and, for sci-fi, pretty straightforward) superhuman abilities, such as super-strength, near-immortality, and energy-blast attacks. Most Eternals look like gorgeous human übermenschen, but Thanos was born with a disease called the Deviant Syndrome, which gave him his massive body, hidelike skin, and distinctively weird creases in his chin. Being surrounded by non-gross people made him resentful of everyone around him, and he grew up into a hateful warlord. He dropped nukes on Titan (he’s particularly proud of killing his mother) and later met Death. He fell in love with her and has worshipped her ever since.

What makes him unique in the supervillain pantheon?
I’ll let Thanos’s creator, writer/artist Jim Starlin, answer this one. “He goes beyond the borders of most other villains,” Starlin told me. “His stories are more metaphysical, more acid-trippy.” I’d add that Thanos is unusual in that he’s rarely depicted as rageful or sullen: He’s usually eerily calm and has a near-constant smirk on his face. He’s a confident nihilist. You can’t negotiate with him. He has nothing to lose. When he’s written well, he’s about as chilling a pulp villain as there can be.

What’s his real-life publication history?
Before he worked for Marvel, Starlin took a psychiatry class in junior college, where he learned about the psychoanalytic concepts of Eros and Thanatos: humans’ drive for living and death, respectively. After class, he doodled a character design and wrote the name “Thanos” under it. “He looked nothing like he looks today,” Starlin recalled. “I’m pretty sure he had the chin, but it was nowhere near as massive a chin or massive a character as he’d go on to be.” Years later, in 1973, 23-year-old Starlin got to write and draw an issue of Iron Man, and he plopped Thanos in as the issue’s villain. The demeanor and origin story were right there, except for the Death romance. (Iron Man thought he’d beaten Thanos, but it turned out Ol’ Purple Chin had duped him by switching places with a robot.)

For decades, Thanos’s importance in the Marvel universe corresponded pretty directly with Jim Starlin’s periods of influence. The Mad Titan got a lot of play in the mid-’70s, when Starlin was a major creative force at Marvel. Those stories got extremely trippy, largely because Starlin was doing lots of acid at the time. When Starlin’s Marvel output tapered off in the ‘80s, Thanos’s presence faded. But when Starlin returned to Marvel in the early ‘90s, he wasted no time in bringing Thanos back into the spotlight with a sequence of repetitively named space epics called Infinity Gauntlet, Infinity War, and Infinity Crusade. Starlin waned, and so did Thanos. But Big Purple made a huge comeback in 2007 with a (Starlin-free) space-opera crossover event called Annihilation, and he’s been a big player ever since. He was at the center of a major Avengers story line called Infinity (sensing a verbal theme here?) in 2013.

What are some notable things he’s done in the Marvel comics universe?
His recurring motif is obtaining and using mystical, Armageddon-level weapons. The first big one was the Cosmic Cube, which could grant wishes. But the weapon he’s most known for is the Infinity Gauntlet. It’s a glove with six stones called the Infinity Gems, each of which represents a different aspect of existence (Mind, Soul, Time, Power, Space, and Reality). When you have all the gems, you have the ability to warp reality itself, and Thanos did just that in Infinity Gauntlet, which remains the most notable Thanos story. The Mad Titan blinked half of the universe’s population out of existence to impress Death, but she wasn’t moved. Enraged, Thanos turned his mind into the living embodiment of the universe, but that left his body briefly vulnerable, so someone else slipped the gauntlet off and brought everything back to normal. (In the Marvel cinematic universe, the Infinity Gems are called the Infinity Stones, for some reason.)

What are his powers?
Like I said, he usually has some kind of super-weapon, and even when he doesn’t, he’s incredibly strong and smart. But other than that, his powers are kind of vaguely defined. Writers don’t really stick to one set of abilities. Sometimes he’s telekinetic, sometimes he can manipulate energy … it’s sort of a grab-bag of sci-fi stuff. That inconsistency of writerly vision is kind of a weakness of the character, to be honest.

How important is he in the Marvel universe?
Very. He’s the most memorable and most used of Marvel’s space-based villains. He’s murdered countless fictional billions. When Marvel heroes find out that Thanos is up to something, they get very, very worried.

What’s he likely to do in the movies?
So far, all we’ve seen him do is act as a puppet master. In a mid-credits scene in The Avengers, we find out he was the one who provided Thor’s nasty brother Loki with the army Loki used to invade Earth. In Guardians of the Galaxy, he sends his prized assassins Gamora and Nebula to help bad guy Ronan. In both cases, Thanos’s deal with the baddies is as follows: I’ll help you if you can get me one of the Infinity Stones. But at last weekend’s San Diego Comic-Con, Josh Brolin wore the Infinity Gauntlet onstage, so things are probably going to look up for the Mad Titan’s quest. The rumor is that Thanos will be the main villain in the third Avengers movie, which will probably come out in 2018. Stay healthy, Josh!

Is there a totally awesome alternate-reality version of Thanos that exists in a self-contained story I can read online for just a few dollars?
I’m glad you asked, because the answer is yes! There’s a great story called “God War” that ran in Ultimate Fantastic Four back in 2006 and 2007. It’s set in an alternate universe, so writer Mike Carey departed a huge amount from the original Thanos concept. But it’s soooooo coooooool and you can read it at Comixology for only 11 bucks.

Are there a ton of amazing images of him looking scary and crazy?
Well, reader, there sure are. Here are some of them.