From Halopedia, the Halo wiki
Tim Dadabo (born March 1961) is an American voice actor, who uses his talents in video games, commercials, cartoons, narration as well as station promo. He has contributed to Leisure Suit Larry and Red Faction since his career began in 1989, but by far his biggest contribution to the gaming world is as the voice of 343 Guilty Spark.
Dadabo voiced Spark in Halo: Combat Evolved and Halo: Combat Evolved for PC, as well as Halo 2 and Halo 3. In addition, he also voiced some of the Marines, such as Corporal Perez. He later reprised his role as Guilty Spark for the terminals in Halo: Combat Evolved Anniversary and Halo 2: Anniversary. Dadabo is also the narrator of the audio edition of Halo: Primordium, which is presented as an autobiographical recounting by 343 Guilty Spark.