From Halopedia, the Halo wiki
Paul Eiding is an American voice actor, voice instructor, and actor. He is most known for portraying the voice of Grandpa Max on the television series Ben 10.
Eiding voiced the SPARTAN's command in the Halo: Reach Beta's Invasion gametype. Eiding is also known in the gaming community as the voices for Roy Campbell in the Metal Gear series, the narrator in Diablo, and Judicator Aldaris in StarCraft. He has done voices in many animations and video games as well as a small number of on screen appearances.