Prophet of Truth

"You are,﻿ all of you, vermin! Cowering in the dirt, thinking... what, I wonder? That you might escape the coming fire? No! Your world will burn until its surface is but glass! And not even your Demon will live to creep - blackened - from its hole to mar the reflection of our passage, the culmination of our Journey. For your destruction is the will of the gods! And I? I am their instrument!"

- - The High Prophet of Truth

The High Prophet of Truth was the leader of the three Prophet Hierarchs that led the Covenant (the others being the Prophet of Mercy and the Prophet of Regret), was the central antagonist in Halo 2 and 3 not to mention one of the main instigators of the war against Humanity.

In 2552, he plotted the ousting of the Sangheili from the Covenant, and replaced them with the Jiralhanae after the death of the High Prophet of Regret on Installation 05. After the demise of the High Prophet of Mercy at High Charity, he became the de facto leader of the entire Covenant, from which position he lead their forces to the Artifact in Africa and eventually to the Ark in an attempt to activate the Halo Array, where he was later killed by the Arbiter.

Trivia

 * His name, Truth, is rather ironic. Prior to the war with Humanity, Truth cheated and lied his way into becoming a hierarch. During the war, he was also prone to lieing to his fellow hierarchs and to the Covenant itself.