Clone troopers, also known as Republic troopers, Republic troops, Republic soldiers, and nicknamed the Boys in White, were highly trained soldiers in the Grand Army of the Republic. Representing the future of galactic warfare, clones were designed to be far superior to battle droids. During the last years of the Galactic Republic, clones formed the backbone of the Republic Military that waged war against the droid armies of the Confederacy of Independent Systems. The Clone Wars was named after the Republic's clone army, which became symbolic of the conflict that had spread throughout the galaxy after a millennium of peace.

Clone troopers were grown on the planet Kamino at the request of Jedi Master Sifo-Dyas, having secretly commissioned the Kaminoans to build an army for the Republic. After his death, the project was taken over by the Sith. Clones were modeled on a human template, the bounty hunter Jango Fett, although their genetic structure was modified to make them less independent and more docile than their progenitor. They were also designed to age at twice the rate of natural humans, accelerating their growth and making them ready for combat in a decade's time. As the Separatist Crisis gave way to open war, the Galactic Senate empowered Supreme Chancellor Sheev Palpatine to call the clone troopers into action, leading to their debut on the battlefield of Geonosis. For three years, clones fought the Separatist droids on all fronts across the galaxy. They were loyal to their Jedi Generals and the Supreme Chancellor; though some clones questioned their service, leading to isolated cases of desertion and treason, most were proud to serve the Republic as it was the only life they had ever known.

Galactic history was forever changed by a hidden behavioral modification biochip implanted in every clone. Chancellor Palpatine, discovered by the Jedi to be the Sith Lord Darth Sidious, issued Order 66—calling for the annihilation of the Jedi Order. With the Jedi labeled as enemies of the state, the clones turned against their generals, slaughtering them across worlds and inside the Jedi Temple on Coruscant under the stewardship of the Sith Lord Darth Vader. Sidious subsequently assumed absolute power as the self-proclaimed Emperor of the Galactic Empire. Clones initially served as Imperial stormtroopers in the New Order, but were soon replaced by human recruits and conscripts. Their armor, weapons, and training inspired generations of white-armored warriors, especially the First Order stormtroopers who were also trained from early childhood to become super-soldiers.