SPOILERS!!
Thanos! Joss Whedon gave us Thanos in the credits to The Avengers! Woo Hoo!
Want to learn more about Thanos, created by Jim Starlin? Here’s a Thanos Reading List (the links are affiliate links back to Amazon, so if you click through and purchase a book I’ll make a small percentage – full disclosure. You may also be able to find these reprints other places for less money):

First Appearance through Captain Marvel years collected in Marvel Masterworks: Captain Marvel – Volume Three

Will be published next year in Essential Captain Marvel, Volume Two:


Reappearance and the Warlock years collected in Marvel Masterworks Warlock: Volume Two


Will be published later this year in Essential Warlock, Volume One


Rebirth and the collection of the Infinity Gems in Silver Surfer: Rebirth of Thanos


The Infinity Gauntlet


The Infinity War


The Infinity Crusade (2 Volumes)



Infinity Abyss


Marvel Universe: The End


Thanos: Epiphany


Thanos: Samaritan


Annihilation




The Thanos Imperative