Darth Desolous, born circa 3522 BBY, was a male Pau’an Jedi Master prior to becoming a Sith Lord. After he studied Sith teachings and fell to the dark side of the Force, he was expelled from the Jedi Order. As the new Dark Lord of the Sith, Desolous swore revenge on the Jedi and assembled an army of Pau’ans, whom he trained in martial arts and used in his fight against the Order. Desolous and his men slew almost two thousand Jedi, until they were crushed by the Jedi Order during a battle on the planet Yaga Minor. During the battle, Desolous was killed. A simulacrum of Darth Desolous was later incorporated into the Jedi Temple‘s Trial of Skill program. In 3 BBY, the program activated itself and fought Sith Lord Darth Vader’s secret apprentice, Starkiller, and was defeated by him.

The character of Darth Desolous was first mentioned on Holocron continuity database keeper Leland Chee‘s blog in 2006, where his name was said to be inspired by the word «desolate.»^[9] No further information was revealed about him until 2008, which saw the release of The Force Unleashed video game. Darth Desolous, appearing as a Jedi simulation, was featured in one of the Jedi Temple levels exclusive to the Krome Studios-developed PlayStation 2, PlayStation Portable, and Nintendo Wii versions of the game, wherein he was voiced by Kristoffer Tabori. In those versions of The Force Unleashed, entering «PAUAN» as a cheat code enables Darth Desolous as a playable character skin. Desolous is also an unlockable character in the PSP version’s «Force Duel» mode.

The exact nature of Desolous’s appearance in The Force Unleashed is rather ambiguous. However, the game’s databank entry for Jedi Trials implies that the simulacrum is projected with the Force, stating that, «Some of the most common trials involved battles against fearsome Force constructs lurking deep within the bowels of the Jedi Temple.» On the other hand, The Jedi Path: A Manual for Students of the Force, a 2010 reference book, describes a holographic projector installed inside the Jedi Temple after the final battle on the planet Ruusan during the New Sith Wars. According to the book, the projector was used during the Jedi Trials by creating simulations of long-dead dark side «monsters.»^[10] The book’s author, Daniel Wallace, later confirmed in his blog that he intended this line to reference Darth Desolous and Darth Phobos—another Sith simulation from The Force Unleashed—but he withheld from spelling their names out in order to avoid any potential timeline conflict.