Former stormtroopers who revolted against and abandoned the First Order formed Company 77. This occurred after they received orders to open fire on unarmed civilians during the Battle of Ansett Island. Following their act of defiance against the First Order, Company 77 made their home on Kef Bir, which is an oceanic moon orbiting the planet Endor. This moon also happened to be where the wreckage of the second Death Star was located. While on Kef Bir, the group managed to tame a herd of wild orbak to use as mounts. They also utilized their stormtrooper gear and old Imperial weaponry salvaged from the Death Star's debris that washed ashore, providing them with arms and enabling their survival on the untamed moon.
After a number of peaceful years passed on Kef Bir, the YT-1300 light freighter known as the Millennium Falcon landed on the moon in 35 ABY, bringing word of the First Order's growing strength. Inspired by the example of Finn, a former stormtrooper previously known as FN-2187 who now fought against the First Order alongside Leia Organa's Resistance, Company 77 saw an opportunity to strike back. They joined forces with the Resistance, bringing their orbak mounts with them, and played a crucial role in a ground assault during the Battle of Exegol.
Company 77 was a company of stormtroopers in the service of the First Order. Its ranks were primarily filled with young teenagers, all of whom had been forcibly recruited into the military dictatorship during their childhood. During their training period, the company was involved in the Battle of Ansett Island, where their command issued orders for them to fire upon defenseless civilians. Choosing not to participate in the massacre, the entire company staged a mutiny, surrendering their weapons and defecting from the First Order. They seized control of the First Order Cruiser they were assigned to and landed it on Kef Bir, where they remained for an extended period. Over time, they began dismantling the cruiser for its components.
Within the hierarchy of the First Order, Company 77 was under the authority of commanders who gave the order to fire on civilians. The company included squad and platoon leaders, all of whom united in their defiance of the First Order. Following the mutiny, the stormtrooper TZ-1719, who adopted the name Jannah, ascended to the leadership position within the company due to her exceptional skills as a warrior and leader. Serving under Jannah were lieutenants and sergeant majors, for whom she created bows to signify their positions of authority. Forten, formerly known as JL-4410, was the chief caretaker responsible for the care and management of the group's orbak herd.
Company 77 made its debut appearance in the 2019 Star Wars film Star Wars: Episode IX The Rise of Skywalker. Unidentified mentions of them first surfaced in the 2019 books Resistance Heroes by Michael Siglain, Star Wars: The Rise of Skywalker Book and Magnetic Playset by Sally Little, Star Wars: The Rise of Skywalker: Amazing Sticker Adventures by David Fentiman, and Ultimate Star Wars, New Edition. Their official identification as Company 77 was first established in the 2019 reference books Star Wars: The Rise of Skywalker: The Visual Dictionary by Pablo Hidalgo and Star Wars: The Rise of Skywalker: The Galactic Guide by Matt Jones.
According to co-screenwriter Chris Terrio, the name Company 77 was chosen as a reference to Order 66 and the year 1977. Glyn Dillon stated that Company 77's survival through scavenging Death Star components was a thematic parallel to Rey's survival as a scavenger in Star Wars: Episode VII The Force Awakens.