Supreme Commander

The rank Supreme Commander is one of the highest Covenant Sangheili ranks. They command large fleets and armadas. Supreme Commander is likely lower in rank, compared to an Imperial Admiral.

For most of the Covenant's history, this rank was held by the Elite race until the Great Schism, when the Jiralhanae assumed most of the higher ranks.

Description
The Supreme Commander commands large Covenant fleets, such as the Fleet of Particular Justice, which was formerly led by Thel 'Vadam, before his failure caused his change of rank to Arbiter. Lesser fleets may be commanded by Fleet Masters, which are a lower rank than the Supreme Commander.

The particular Supreme Commander in the aforementioned text was a friend of, and yet superior to, Special Operations Commander Rtas 'Vadumee, and would later become the Arbiter.

During the Civil War of the Covenant, it is possible that Jiralhanae took these positions from the Sangheili, but none have ever been seen, as the majority of the other posts were taken over. However, some Elite Supreme Commanders may have escaped to fight the Brutes.

Appearance
When commanding a Fleet, Supreme Commanders were wearing gold armor signifying the Zealot range of ranks, with a purple cloak that wraps around and over the armor piece of their shoulders, and a showy helmet, probably with ceremonial purpose. The Supreme Commander's unusual helmet looks somewhat similar to the Halo 3 Sangheili Combat Harness when compared closely. However, when Thel 'Vadamee appears before the Covenant High Council, he sports golden Zealot armor without a purple cloak. This may signify that the purple cloak is only for those who command fleets, or that he resigned from his position.

Trivia

 * Thel 'Vadam was the only known Supreme Commander in the Halo universe.
 * Supreme Commander may be a type of Zealot, as the term "Zealot" appears to be a blanket rank covering various positions, and Thel was in a Zealot armor suit when he was in the Council Chamber.