The Marvel Cinematic Universe is a shared film franchise based on Marvel comic characters. It began with Iron Man in 2008 and includes over 20 films organized into story arcs. Marvel Television expanded the universe with shows on ABC, Netflix, Hulu, and other networks. Marvel Comics began in 1939 and featured many iconic heroes created by Stan Lee in the 1960s. Key characters that appear across films include Iron Man, Captain America, Thor, Hulk, Black Widow, and Spider-Man. Avengers: Infinity War and Endgame told a two-part story involving Thanos' quest for the Infinity Stones and the heroes' attempt to reverse his actions.