(Warning - SPOILERS for multiple Marvel comic books, and quite possibly Avengers: Infinity War, lie below. Proceed with caution, and all that jazz...)
Now, as of yet, the Guardians of the Galaxy may be the only members of the Marvel Cinematic Universe to actually have the slightest idea of who Thanos is (and even then, most of them only know him by reputation), but with Avengers: Infinity War very much on the horizon, that's all likely set to change real soon.
After all, as the final moments of both Avengers movies thus far have made achingly clear, Thanos is coming - and if the comic books are any guide, then he's going to do some pretty fundamentally terrible things when he gets here...
As a result, it's probably time to take a close look at just how dark things have gotten in Thanos' comic book past, with a list-based look at:
5 of the Worst Things Thanos Has Ever Done
Which, as fans of Marvel comic books from the '90s can attest, is a tough subject to narrow down to just five...
First up, then?
5. He Betrayed His Family
Born on Titan, one of Saturn's moons, Thanos was a member of a genetically-altered race of humans named the Eternals (with his particular colony's Eternals often being referred to simply as Titans) known for their external perfection. Thanos, however, was born with a genetic mutation known as Deviant Syndrome, which left him with his distinctive purple skin and peculiar chin.
His parents - A'Lars, ruler of Titan, and Sui-san - could do little to stop him growing into a difficult and nihilistic young man...who eventually betrayed his people, stealing one of their starships, and heading off into space.
The youthful Thanos didn't stop there, though...
4. He Destroyed His Home World
Soon, Thanos returned to Titan...with a private army, and a whole lot of nuclear weapons. He proceeded to bombard his home world, killing all but a handful of his people.
His proudest accomplishment that day? Successfully killing his own mother...
Next up, though?
3. He Fell in Love with Death
Which, in and of itself, isn't all that bad when you really think about it: after all, the heart wants what the heart wants - even if that's the physical embodiment of the abstract concept of death. The only problem?
Death wasn't as into Thanos as he was into her, and her rejection may have led to a teensy bit of mass galactic genocide.
Y'see, pretty much all of Thanos' worst (and most bloody) deeds were done in the name of impressing his love - by killing for her.
Speaking of which:
2. He Killed All of Your Favorite Heroes
That's right - back in the legendary Infinity Gauntlet crossover event, Thanos successfully killed pretty much every hero you've ever loved...
...often in horrifically cruel seeming ways:
Note - that's Iron Man's head, just kind of...sitting there.
Now, of course, the heroes were all returned to life not too long after - but for a minute there, there really wasn't a more successful hero killer than Thanos.
Even worse, though?
1. He Quite Literally Killed Half the Universe
As in, right around the time he killed all those heroes, he also killed half of the universe.
As in one in every two people.
With a click of his (Infinity Gauntlet-clad) fingers.
Just to impress Death.
Now, once again, they ended up being restored to life after Thanos was later defeated - but even so...
That's a fundamentally horrifying thing to even conceive of, let alone actually do...
But, then again...That's Thanos For You...