From Halopedia, the Halo wiki
Pete Stacker is a voice-over actor in Chicago. Stacker is best known as the announcer on the Real Men of Genius campaign for Bud Light. He is also the announcer for the Oprah Winfrey Show, Comedy Central and Country Music Television. Besides his commercial work he does video game voice acting, and is most famous for playing Captain Jacob Keyes from Halo: Combat Evolved and Halo: Reach, as well as Gunnery Sergeant Marcus Stacker in Halo: Combat Evolved, Halo 2, Halo 3, Halo 3: ODST, Halo: Reach and Halo 4. He has also voiced several other characters, such as an NMPD officer tasked with the defense and destruction of the ONI Alpha Site in Halo 3: ODST, and Echo Four, a Sabre pilot in Halo: Reach.