A rancor held by Boba Fett, known as Boba's rancor, was presented to him by the Twins, who were Hutts. As part of the Twins' tribute, a rancor keeper came to Boba Fett's Palace with the rancor to assist Fett in its care. After learning that the Witches of Dathomir were known to ride rancors, Fett stated that he wanted to learn how to ride the rancor.
Around 9 ABY, the Twins, a pair of Hutts, gifted the rancor to Daimyo Boba Fett. The Twins' tribute included the arrival of a rancor keeper at Boba Fett's Palace to help Fett care for the rancor. The keeper told the former bounty hunter that the rancor would create a bond with the first Human it saw. Upon hearing that the Witches of Dathomir had a history of riding rancors, Fett voiced his desire to learn how to do the same. The keeper then instructed Fett to stand before the rancor as he removed its blinders, curious as to what name he would give his new pet. It immediately noticed Fett and imprinted on him after regaining its sight. Fett started petting the animal and discovered the location it enjoyed being rubbed the most, which was next to its right eye, as he easily approached the rancor. However, at that precise moment, 8D8 broke in to inform them that Mayor Mok Shaiz would not be available for the following 20 rotations. The rancor seemed disappointed as Fett left to feed it and confront the mayor. But the rancor keeper gave it reassurance that Fett would return.
Fett then kept the rancor in the rancor pit at Jabba's Palace and used it to scare the crime lords of Mos Espa when one of them threatened to kill him. Fett was able to calm his pet down by feeding it, but he also threatened the other bosses by implying that he would feed them to it and that it was hungry. The rancor turned into Boba's own mount during the Battle for Mos Espa. He used it to aid in the destruction of the two Scorpenek annihilator droids that the Pyke Syndicate had unleashed. Fett was thrown off in the fight, and the rancor started scaling the city's structures. The Force-sensitive youngling Grogu then subdued the rancor and put it to sleep, ending its rampage and saving its life, even though the allied fighters tried to shoot it.
The rancor made its debut in "Chapter 3: The Streets of Mos Espa," from The Book of Boba Fett live-action TV series.