Callef was a Human male Dark Jedi who lived during the Cold War between the Galactic Republic and the Sith Empire. The apprentice of the Dark Jedi Bengel Morr, Callef and his master rallied the native Flesh Raiders of the planet Tython in an attempt to destroy the Jedi Order. During the early stages of the Flesh Raider uprising, he led his Flesh Raider soldiers in an attack on the Jedi base in the Tythonian Gnarls, and captured a Bith apprentice by the name of Unaw Aharo. However, Callef was killed in a duel with another Jedi apprentice who came to rescue Aharo.