The Covenant separatists were the Sangheili-led forces that seceded from the Prophet-led Covenant during the Great Schism. In November 2552, the Prophet of Truth had the Sangheili removed from their former position and replaced by the Jiralhanae as the Covenant's main military caste, resulting in an open war breaking out between the Jiralhanae-led forces loyal to the Prophets and the Sangheili. After the Sangheili learned the truth about the Halo Installations near the end of the Battle of Installation 05, they allied with humanity on their mission to stop the Prophet-led Covenant.
As they no longer looked to the Prophets for leadership, the separatists had no defined leadership, although Arbiter Thel 'Vadam and Shipmaster Rtas 'Vadum led their forces in the deciding battles of the war. With the Covenant dissolved, the separatists effectively ceased to exist as a unified force. The Sangheili returned to their homeworld and splintered into various factions, with the Arbiter and his policy of cooperating with humanity retaining a solid following, although many Sangheili disagreed with his ideals, planning to overthrow the Arbiter and rise against humanity.
The Covenant separatists are made up of the Sangheili, along with some Unggoy and Mgalekgolo loyal to them. At the onset of the Great Schism, the separatists began fighting the forces loyal to the Covenant, led by the San 'Shyuum with Jiralhanae, Yanme'e, Kig-yar and some Unggoy and Mgalekgolo loyalists.
This disgruntled faction is led by the Arbiter Thel 'Vadam and Shipmaster Rtas 'Vadum, since the highest-ranking Sangheili military leader, Imperial Admiral Xytan 'Jar Wattinree was killed by a NOVA bomb soon after announcing the separation of the Sangheili from the Covenant. It is possible the remaining Councilors command the faction from Sanghelios as aides to the Arbiter, offering their counsel to him as they once did with the San 'Shyuum. Fronts of this war include the Covenant holy city of High Charity, Installation 05, Earth, the Ark, and areas of space where Covenant ships operate.
The High Prophet of Regret led a badly planned mission to Earth, against the wishes of the High Prophet of Truth, and was subsequently forced into the Battle of Earth, as he did not know that the planet was the human homeworld. He escaped to Installation 05, where he was killed by John-117. Regret's death was used as a justification by the remaining Prophets to replace the Sangheili with Jiralhanae as their protectors. However, this move resulted in great turmoil within the Covenant, with the Sangheili threatening to resign from the High Council.
Truth then gave command of the Covenant fleets, the post previously held by the Sangheili, to the Jiralhanae. Once there were enough of them in place, Truth secretly ordered them to commit a vicious genocide of the Sangheili (disguised as a retaliation to an Sangheili revolt against the other Covenant factions) so they may replace them in society. The Sangheili responded, with the help of factions of Mgalekgolo and Unggoy, and war broke out in High Charity with Jiralhanae and Sangheili fleets fighting each other in space around it. Later, most of the Sangheili Councilors were assassinated by the Jiralhanae at the behest of the Prophets.
 Sangheili-human alliance
The Unggoy were too indecisive to continue the rebellion and the true political motivation of the Mgalekgolo, if any, remains a mystery, although Mgalekgolo pairs could have followed the Sangheili they protect. The shaky-to-steady alliance between the separatists and their former foes, the humans, was forged entirely out of necessity. The UNSC forces were on the defensive, and both factions had two common enemies that wished for their extinction: the Covenant and the Flood. The alliance of circumstance was forged in the control room of Delta Halo, when UNSC Sergeant Major A. J. Johnson and the Arbiter were coerced to unite in order to prevent Tartarus, Chieftain of the Jiralhanae, from activating Installation 05. After that, the Arbiter persuaded the rest of the Sangheili to join humanity. While the two factions experience some friction, they learn to work with one another for their mutual survival. By the end of the Human-Covenant War, the Sangheili fight alongside humans in battle and save them from destruction.
The devastated UNSC Home Fleet defending Earth were glad to accept the help of the superior separatist warships. The Sangheili' understanding of enemy equipment and Covenant's combat tactics proved invaluable in the Battle of Installation 00. Recurrently the heroes of the battle, Thel 'Vadam and John-117, fought alongside one another many times in the desperate and long conflict.
 End of human-Covenant War
With Truth dead, High Charity destroyed, and Installation 00 essentially lost to the reborn Installation 04 firing, what remained of the Covenant was all but destroyed, with its member species divided into multiple factions. In the wake of the conflict, the Arbiter and his allies remained friendly to humanity and wished to build mutual peace, as they both had made tremendous sacrifices in order to stop Truth and the Covenant forces. On their homeworld, however, they were challenged by a resurgent faction of religious fanatics known as the Servants of Abiding Truth, who viewed the Arbiter's allies as "blasphemers" and began an insurrection, secretly with the support of the UNSC Office of Naval Intelligence. The Abiding Truth managed to gather a large amount of followers in a relatively short timespan; while the faction had a strong religious underpinning, many Sangheili had more practical motives for allying against the Arbiter, among them resentment toward humanity.
Over the next six years, the Sangheili continued to wage war against the remaining San 'Shyuum and the Jiralhanae. At first, the Sangheili were at a major disadvantage, as millennia of depending on the San 'Shyuum for technology meant that the Sangheili were unable to properly repair or replace the ships they lost in battle. The odds began to even out when the San 'Shyuum "vanished" and the Jiralhanae began to fall back into internecine conflicts.
 Military forces
 Other notable members
Though the Covenant separatists were called "Heretics" by the High Prophet of Truth, they should not be confused with the heretic faction led by the Sangheili Sesa 'Refumee and destroyed by Arbiter Thel 'Vadamee, although they do have the same goal and beliefs. If remnants of the heretics were still around during the time of Halo 3, they and the separatists would be on the same side, since the heretics also knew the truth about the Halo Array.
 List of appearances
- Halo 2 (First appearance)
- Halo: Ghosts of Onyx
- Halo 3
- Halo: Evolutions - Essential Tales of the Halo Universe
- Halo: Glasslands
- ^ Halo 3, campaign level The Storm
- ^ a b c Halo 2, campaign level The Great Journey
- ^ a b Halo 3, campaign level Floodgate
- ^ a b Halo: Glasslands
- ^ a b Halo 2, campaign level Uprising
- ^ Halo: Ghosts of Onyx, page 240
- ^ Halo 2, campaign level Gravemind
- ^ Halo 3, campaign level The Ark
- ^ a b Halo 3, campaign level The Covenant
- ^ Halo: Evolutions - Essential Tales of the Halo Universe, "The Return"