Zachary Paul De Villiers Theart (born 27 May 1975) is a South African singer, songwriter, and the former lead vocalist for the British power metal band DragonForce and American rock band Skid Row. Theart was also hired by Riot Games for the voice of Karthus in the songs "Deathfire Grasp" and "Last Whisper" by the metal band Pentakill.