Arbiter

Arbiter is a title held by Elites who have been disgraced and go on suicidal and potent missions to regain their honor in death. There have been many Arbiters, but the most famous is undoubtedly Thel Vadam.

Thel Vadam
The Arbiter is the current General of The Army of The League and the awesome boss of the Elites. He is also a member of League High Command. He was once the Supreme Commander of the Covenant Fleet of Particular Justice but was disgraced by the Prophet of Truth and made Arbiter. Disappointed, he decided to become Arbiter in an attempt to regain his honor, and was let lose against the Heretic faction, led by Pretzel King. After killing Pretzel King the Prophets ordered him to find them the Sacred Icon, i.e. the Acticvation Index for Halo Installation 05. He did so but realised that the Prophets had simply distracted him whilst they let the Brutes attack the Elites.

He vowed his vengeance and the Elites rallied by his side when the Prophet betrayed them. He killed Tartarus, chieftain of the brutes, with his own hammar and allied himself and the Elites with the Human in the process. After draining some of Johnson's invincibility and gaining awesome powers, he rallied his forces around the Shadow of Intent and, with Shitmaster, Miranda, Johnson and Guilty on board, they left for Earth.

On Earth Arby met Johnny, and they travelled across Africa together on a montage, killed Covvies wherever they went. Arby also helped him fight off a Flood infestation. They chased Truth to the Ark and bullied his forces there. They allied with the Flood to break through Truth's Citadel, Arby later killed Truth by slowly gouging him to death, and bore witness to Truth's last laugh against Humanity, which consisted of his head spinning off his body like a helicopter and biting Lord Hood's nose off. Arby was not even slightly fazed by this, nor was he fazed by the Gravemind's inevitable betrayal. Arby helped Johnny stop Guilty Guilty from destroying the Universe and was with him when they escaped the new Halo. However, Johnny was seperated from Arby and landed on Requiem. Arby now lives on Sangheilios with his pal, the Shitmaster, and his nine thousand million wives, but he occasionally ventures out to do his job of commanding and fighting alongside the Army of The League.

Other Arbiters
There was also another Arbiter that discovered a Shield World similar to Requiem, which was infested with Flood. He fought Captain Cutter but was eventually killed by Sergeant 'Badass' Forge. His name was Ripa Moramee, and he was apparently eight feet tall, which is pretty tall.

According to the withered Prophet of Mercy, there were Arbiters that stopped a Grunt Rebellion and tamed a bunch of Hunters.