Thanos is a fictional supervillain appearing in American comic books published by Marvel Comics . The character, created by writer/artist Jim Starlin , first appeared in The Invincible Iron Man #55 ( cover dated February 1973). Thanos is one of the most powerful villains in the Marvel Universe and has clashed with many heroes including the Avengers , the Guardians of the Galaxy , the Fantastic Four , and the X-Men . The character appeared in the Marvel Cinematic Universe , portrayed by Damion Poitier in The Avengers (2012) and by Josh Brolin in Guardians of the Galaxy (2014), Avengers: Age of Ultron (2015), Avengers: Infinity War (2018), and Avengers: Endgame (2019) through voice and motion capture. The character has also appeared in various comic adaptations, including animated television s...