Robbing from a post from Bouncy -
Thanos appears in a scene played during the end credits of the Avengers film.He is revealed to be the one who provided Loki with the Chitauri army. When told by his accomplice (known simply as "The Other") that battling The Avengers would be to court Death, Thanos flashes an evil grin. Thanos does not speak in this appearance.
Pretty much a setup for the sequel
'Dead tree technology!
Information that , if carefully stored , would last for millennia! And no batteries required.'
'There is no future for e-books, because they are not books. E-books smell like burned fuel.'
Ray Bradbury (RIP)