Thanos, perhaps Starlin's greatest creation, was originally inspired by Jack Kirby's Darkseid (of the New Gods fame). Because of Judo Jim's deft handling of Thanos' personality, ol' purple puss went on to become one of the greatest villains of the Marvel Universe. He was the linchpin that connected the Captain Marvel and Warlock series, and went on to become perhaps Marvel's major villain of the 1990s (remember all of those Infinity cross-overs?). Many people say there were two major Marvel characters created in the 1970s: Wolverine and the Punisher. I say there were three, 'cause Thanos ranks up there with Wolvie and Frank Castle as a major player in the M.U. (And yeah, Ghost Rider ranks fourth, but let's not get carried away...)
I wanted to send 2008 out with a bang, and it don't get any bangier than this, baby! From 1977, here are Avengers Annual #7 and Marvel Two-In-One Annual #2 by Starlin and Joe Rubenstein! Prepare to have your mind majorly blown!