Hard to believe that Marvel did ten years of movies, up to and including the Infinity Gauntlet and never bothered to properly introduce Warlock.
Yeah, it is kind of odd they wouldn't exploit a character so popular into their movies and other licensing. Although Starlin's WARLOCK wasn't a big seller when it came out, it certainly is now. There's a few comic book/graphic novel trades that I consider on a par with Pink Floyd's
Dark Side of the Moon album, that consistently ranks among the 100 best selling albums even decades after its 1971 release. And Starlin's WARLOCK is certainly among them, along with Alan Moore's WATCHMEN and V FOR VENDETTA, and Miller's DARK KNIGHT RETURNS and DAREDEVIL:BORN AGAIN.
I wasn't surprised when Thanos showed up in the Marvel movies. Maybe they're just waiting for the right moment to bring in Warlock.
