Kosa-Yin Hadu was a Gungan male Sith cult member who lived during the waning years of the Galactic Republic. Originally a member of the Jedi Order, Hadu trained as the Padawan of Jedi Knight Kin-Ya Dosun, a fellow Gungan. In about 33 BBY, the pair was dispatched on a mission from the Jedi Temple on the planet Coruscant, but they subsequently disappeared. At some point, Hadu fell to the dark side of the Force and became a member of the Believers, a Sith cult that was based on the planet Almas. Circa 31 BBY, Hadu and the Mon Calamari Dark Jedi Gar Granga were sent by Garvin Delquist, the leader of the Believers, to poison Almas's kaluthin plants as part of a Believer plot to drive the Jedi—who operated a training facility on Almas—off the planet. However, the plot was uncovered by a group of