The 501st Legion is an international fan-based organization dedicated to the construction and wearing of screen-accurate replicas of Imperial Stormtrooper armor, Sith Lords, Clone Troopers, bounty hunters, and other villains from the Star Wars universe. The 501st Legion, called by its nickname Vader's Fist, is made up entirely of volunteers.

Stormtroopers are soldiers in the fictional Star Wars franchise created by George Lucas. The term originates from the original SA of the Nazi party in Germany before Hitler's rise to power, Sturm Abteilung (Stormtroopers) abbreviated to SA. Introduced in the original Star Wars film, the stormtroopers are the shock troops/space marines of the autocratic Galactic Empire, under the leadership of Emperor Palpatine and his enforcers, most notably Darth Vader and Grand Moff Tarkin, during the original film trilogy (1977–1983) and Rebels (2014–18). The prequel trilogy (1999–2005) and The Clone Wars (2008–2020) explores their predecessors in the Galactic Republic's clone troopers, clones of the bounty hunter Jango Fett, used by Supreme Chancellor Palpatine to "win" the Clone Wars and later to take over the government and exterminate the Jedi. After this, in The Bad Batch (2021–2024), stormtroopers are established as human recruits, trained by clone troopers gradually being phased out of active service; at the time of the original trilogy, only a few stormtroopers are clones, with the only known legion to still contain a significant number of clones being the 501st Legion, a.k.a. "Vader's Fist", with many stormtroopers remaining in service to Imperial remnants following the Empire's fall under Moff Gideon and Grand Admiral Thrawn in The Mandalorian (2019–present) and Ahsoka (2023). In the sequel trilogy (2015–2019), the First Order employs stormtroopers under the leadership of Supreme Leader Snoke and his enforcers, most notably Kylo Ren, General Hux, and Captain Phasma.