Thel' Vadam (formerly known as Thel' Vadamee), is the Sangheili Kaidon of the Vadam family and was an Arbiter during the closing days of the Human-Covenant War. He has commanded fleets, and is responsible for the Sangheili uprising against the Hierarchs after he and his race were betrayed by them and the Jiralhanae. He is also responsible for the death of Tartarus, which allowed UNSC forces to stop the Halo Array from firing. In the final battle of the war, 'Vadam, along with John-117, prematurely fired Forerunner Installation 04B, destroying the Ark.