Ooskoo (Birth name unknown) was a former Sangheili Field Marshal in the Covenant Army during the Human-Covenant War. He joined the Covenant Remnant group, Servants of the True Reclaimers. While he was in the group, he led a rebellion against the radical ruler, Raghath and allied himself with humanity to prevent the firing of Installation 02. He led a small group of rebels on Installation 02 against Raghath but was ultimately killed during the fight.