Terence Stamp
From Halopedia, the Halo wiki
Terence Stamp played the voice role of the Prophet of Truth in Halo 3 replacing Michael Wincott who played the role for Truth in Halo 2.
Alongside Halo 3, Stamp also has portrayed several other characters, many of them being villains. He has also been nominated for an Academy Award.
In live action films, Stamp portrayed General Zod in Superman II, Chancellor Valorum in Star Wars Episode I: The Phantom Menace, Stick in Elektra, Siegfried in Get Smart, and other films such as Red Planet , Yes Man, and My Boss' Daughter.
Stamp also lent his voice in animated features and video games. In addition to Truth, Terence Stamp also played another key video game antagonist, Mankar Camoran, in the Elder Scrolls IV: Oblivion.
In the Halo 3 Legendary Edition bonus disc one can see him voice acting as the Prophet of Truth, giving a speech to Covenant as John-117 and the Arbiter enter Installation 00's Citadel.
