From the Super Mario Wiki
Charles Martinet (last name pronounced mar-tin-AY), born September 17, 1955 in San Jose, California, United States of America, is a prominent voice actor of the Mario games. He voices several major characters, including Mario, Luigi, Wario, Waluigi, Baby Mario, Baby Luigi, Baby Wario, Metal Mario, Toadsworth, and many other characters. Martinet portrayed the male bosses in Super Mario Advance as well. Martinet plays the vast majority of the male characters in the Mario series. The Internet Movie Database attributes over 150 works to Martinet in total. Martinet speaks fluent French, English and Spanish, but, ironically, only a little Italian. His first voice over work at Nintendo was voicing the announcers, boxers and the referee in Super Punch-Out!! for the SNES.
Martinet originally was not invited to audition for the role of Mario. He crashed the auditions, and was asked to do an Italian accent. His recordings left so much of an impression that they were the only one sent to Nintendo. A former Shakespearean actor, Martinet has stated that Mario's voice was based on his voice for Gremio, a character from The Taming of the Shrew.
Martinet first officially voiced Mario in the Super Mario Bros. pinball machine in 1992, though he was uncredited in the game. The next time he portrayed Mario, and the first time as several other characters, was for Mario in Real Time in 1994, when he had motion sensors hooked to his face, which transposed his facial movements to a computer-generated Mario head on a screen. Martinet watched people passing by the screen through a surveillance camera and talked to them as Mario. This is used rather often by Nintendo when attending trade shows. An altered form of Mario in Real Time appeared in 1995's Mario's Game Gallery (later reissued as Mario's FUNdamentals), which is the first video game to have Mario portrayed by Charles Martinet.
Portrayals (Mario-related media)