Rtas 'Vadum (known as Rtas 'Vadumee before the Covenant Civil War) was a Sangheili Commander of the Covenant army before the Great Schism, and after Great Schism he served as Shipmaster.
He was the only known Special Operations Commander of the Covenant Army in the Halo series, a title in which he served before the civil war. As the Ship Master of the Shadow of Intent and the de-facto commander of the Fleet of Retribution, he had a pivotal role during and after the Battle of Installation 05.
While Blade was captured and held aboard a Brute CCS Class Battlecruiser, (His capture initiated after the liberation of Vaz from an ONI facility), Rtas 'Vadum was seen in the cell next to him. When Rose came aboard disguised as a prisoner to rescue him, Rtas was also rescued with the two of them. He helped them take down a pair of Brute Chieftains that trapped them, then killed one of the Jiralhanae Alpha Tribe leaders that made the mistake of dualing him alone. The Alpha leader seems to have had a previous encounter with Rtas, as he referred to him by name and possessed his Energy Sword, which he returned for the duel. Rtas decapitated the Chieftain's gravity hammer, and impaled the Chieftain with his blade, later returning to the Forest of no return with Rose, Blade, and their captor.