Imperial Admiral

Imperial Admiral is a Covenant Sangheili (Elite) rank. They command large fleets of Covenant cruisers

Rank
An Imperial Admiral operates on a high ranking Covenant Flagship such as an Assault Carrier, Supercarrier, or other very powerful capital ships within the Covenant armada. They seem to be higher ranked than a Zealot, as Xytan 'Jar Wattinree promoted Voro Nar 'Mantakree, but this is not known for sure. It is revealed in Halo: Ghosts of Onyx that the Imperial Admiral controls the entire fleet of the Covenant. Little else is known about the rank other than that. It has been featured in one book, so little information can be given.

Appearence
Their armor is silver covered with the gold Forerunner glyphs of sacred mystery, much like the Arbiter's. Such silver-and-gold Elite armor has been seen in Halo 3 and mentioned in Ghosts of Onyx, and is superior in quality to the gold armor of a Zealot. Such questions have been spun and this combination maybe belonging to the fabled rank of Zealot Ultra. Xytan also travels with a large hologram of himself, and it is unknown if other Imperial Admirals do so, or if this is just something he has a habit of doing. They wear a headress for ceremonial purposes, like a Sangheili Councilor.

Trivia

 * Imperial Admirals are just above Supreme Commanders and just below Councilors.