6 Underground is a 2019 American vigilante action thriller film directed by Michael Bay and written by Paul Wernick and Rhett Reese. The film stars Ryan Reynolds, Mélanie Laurent, Manuel Garcia-Rulfo, Adria Arjona, Corey Hawkins, Ben Hardy and Dave Franco. Bay produced the film with his longtime business partner Ian Bryce and Skydance's David Ellison, Dana Goldberg and Don Granger. It follows a group of people who fake their deaths and decide to form a vigilante team in order to stage a coup d'état against a ruthless dictator.

6 Underground premiered at The Shed in New York City on December 10, 2019, and was released by Netflix on December 13, 2019. With a budget of $150 million, the film is one of the most expensive Netflix originals ever made. Rotten Tomatoes called it "loud, frenetic and finally preposterous".