The big tenth anniversary Marvel movie, Avengers: Infinity War, is just around the corner. If you are on this site, and were somehow living under a rock, the movie will finally show off the big, bad villain Thanos who first appeared in the Marvel Cinematic Universe in the first Avengers movie as a tease. The directors of Infinity War have stated that the movie is basically from Thanos' perspective and did give the broad strokes of his origin (different from the comics version) before (SPOILERS if you want to go into the movie clean):
"He's from a planet called Titan. Many years prior to the film his planet was experiencing a cataclysmic shift. They were running out of resources, and they were overpopulated. Thanos made a recommendation that they exterminate half the population randomly in order to save the rest of the population. Of course, the Titans rejected his notion, branded him a mad man, exiled him, and the planet ended up dying. So he has taken it upon himself to go planet-by-planet throughout the universe and wipe out half of the population of each planet as a way to correct the planet and bring it back into balance. Once he hears about the stones, he realizes that if he can get hold of all of the Infinity Stones he can control the entire universe. With the snap of his fingers he could correct the universe permanently by removing 50 per cent of life from it. So, these are incredible stakes for our characters. If the Avengers were built for anything, it's for stopping Thanos from completing his goal."
We will be getting a more fleshed out version of the origins of Thanos, but that version of the story will not be in movie form, rather than in a book. Sister Disney property Star Wars has its unified canon, which has (almost) all of its products (eg. comics, novels, television, movies) sharing the same universe. With this upcoming book, it seems like Marvel might be trying this kind of continuity out, as the book will be considered "canon" to the Marvel Cinematic Universe.
Here's the summary for the book Thanos - Titan Consumed by Barry Lyga (ANOTHER SPOILER WARNING! The last third of the summary may be spoiling Avengers: Infinity War in a big way):
Space. Reality. Mind. Power. Time. Soul.
Before creation itself, there were six singularities. Then the universe exploded into existence, and the remnants of these systems were forged into concentrated ingots...
Only beings of immense power can hope to wield these stones, but for those who are worthy, the powers of a god await.
Thanos is one such being. But he wasn't always.
Born on a doomed world and cast out by his people for his genius, physical deviancy, and pragmatic but monstrous ideas, Thanos is determined to save the galaxy from the same fate as his homeworld... no matter how many billions have to die.
Learn the origins of the most formidable foe the Avengers, the Guardians of the Galaxy, Doctor Strange, and Black Panther have ever faced—a foe whom even a group of remarkable people, pulled together to fight the battles nobody else could, will fail to stop....
Dread it. Run from it. Destiny still arrives.
Thanos is here.
Lyga says that there will be nods to events from the different Marvel movies weaved into the book:
"That was one of my main goals in the novel and, in fact, was the main reason I agreed to write it! I really hope that certain bits in the book will make people go, “Oh, so now that cool scene from that one movie is even cooler!” I really wanted to reverse-engineer those moments we’ve all seen already—in Guardians, in Avengers—and show how we got to them."
You can get consumed by Thanos - Titan Consumed when the book invades booktores in November.
Thanos - Titan Consumed cover