Illidan Stormrage was once a Night Elf who turned into a Demi-Demon. One of the most prominent characters in the Warcraft video games. Illidan has an addiction to magic and is an outcast by his fellow Night Elf people. He is the twin brother of Malfurion Stormrage and he is also one of the most powerful fighters in the Warcraft universe.
He was originally voiced by Matthew Yang King for Warcraft III: Reign of Chaos and the expansion pack for Warcraft III: The Frozen Throne (cinematics and game play). Yang was unable to reprise the role for future games due to guild union issues.
Next we have Liam O'Brien who voiced Illidan for World of Warcraft: The Burning Crusade.