The narrator in Fallout, Fallout 2 and Fallout Tactics was Ron Perlman, a quite well known hollywood actor. He did not voice Fallout: Brotherhood of Steel. He narrated the game intro and the endings for various towns in the games.
Although it is not yet entirely certain whether Perlman will narrate Fallout 3 or not, Todd Howard of Bethesda assured the fans that Perlman still does voice-overs for games in a 2005 Duck and Cover interview.
Perlman also voiced Butch in Fallout.