Lost Twenty

The Lost Twenty referred to the group of Jedi Masters, numbering twenty in total, who had renounced the Jedi Order throughout its history. One notable and the twentieth member of the Lost Twenty was the Sith Lord Count Dooku, who had abandoned the Jedi after the death of his former Padawan, Qui-Gon Jinn, at the Battle of Naboo in the years preceding the Clone Wars. Dooku, having also become disillusioned with the Galactic Republic, peacefully left the Jedi Order while secretly pledging his allegiance to the Sith as Darth Tyranus. Dooku, along with the rest of the Lost Twenty, was commemorated with a statue bust in the Archives of the Jedi Temple on Coruscant.

Behind the scenes
"I never understood why he quit.''" "''Well, one might say he was always a bit out of step with the decisions of the Council."

- Obi-Wan Kenobi and Jocasta Nu discuss Dooku in a deleted scene titled "The Lost Twenty"

The Lost Twenty were originally introduced in a deleted scene of the 2002 Star Wars film Star Wars: Episode II Attack of the Clones. In the scene, likewise titled "The Lost Twenty," the Jedi Knight Obi-Wan Kenobi, while searching through the Jedi Archives, observed the bust of Dooku alongside the librarian Jocasta Nu. The pair discussed Dooku's departure from the Order and his recent resurfacing as the leader of the Secessionist Movement.

References to the Lost Twenty were made in various products of the Star Wars Legends brand, but they were not reintroduced into the Star Wars canon until the release of the 2015 reference book Star Wars: Absolutely Everything You Need to Know, in which the question "Who are the Lost Twenty?" is answered.