Thanos is shaping up to be the Marvel Cinematic Universe's biggest villain, with Avengers: Infinity War promising an epic showdown between the galactic overlord and what sounds like every hero on the Marvel roster. But while the character was first introduced in 2014's smash Guardians of the Galaxy, director James Gunn has revealed that he won't play a part in the sequel.During a Facebook Q&A, Gunn was asked if Thanos would return for 2017's Guardians of the Galaxy Vol.