Legion is an American superhero television series created by Noah Hawley for FX, based on the Marvel Comics character of the same name. It was produced by FX Productions in association with Marvel Television, and ran for three seasons from 2017 to 2019, with Hawley serving as showrunner.

Dan Stevens starred as David Haller, a "mutant" diagnosed with schizophrenia at a young age. The series follows Haller as he tries to control his mutant powers and the sinister forces trying to control them while evading a government agency. Rachel Keller, Aubrey Plaza, Bill Irwin, Jeremie Harris, Amber Midthunder, and Jean Smart also starred, along with Katie Aselton during the first season. For the second season, Jemaine Clement and Hamish Linklater were promoted to main cast after having recurring roles and Navid Negahban joined the cast. Lauren Tsai joined for the third season.

FX and Marvel Television announced a new collaboration to create a television series based on the Marvel Comics character Legion in October 2015, with Hawley signed on to write and direct the pilot. He wanted to show Haller as an "unreliable narrator", including mixing 1960s design with modern-day elements, and filming the series through the title character's distorted view of reality.

The eight-episode first season of Legion aired from February to March 2017. An eleven-episode second season aired from April to June 2018. The eight-episode third and final season premiered on June 24, 2019. A total of 27 episodes aired over three seasons. All three seasons received critical acclaim for their distinct narrative structure and visual style, as a unique approach to the superhero genre.