The multiverse is a setting within the Marvel Cinematic Universe (MCU) media franchise. Based on the setting of the same name from the Marvel Comics, it is a collection of infinitely many alternate realities and dimensions. First explored in the film Doctor Strange (2016), it is revisited in the film Avengers: Endgame (2019) before playing a key role in Phases Four, Five, and Six of the MCU, which constitute "The Multiverse Saga". The MCU's multiverse centers on a universe called the "Sacred Timeline". Initially, alternative universes were generally "pruned" by the Time Variance Authority (TVA), until Sylvie kills TVA's leader, "He Who Remains", allowing new universes to fully form. Following this, the TVA under new management instead nurtures and observes these new universes. Occasionally, some universes are considered separate from the "Sacred Timeline" but still monitored by the TVA.