- "You're going to blow the hotel sky high, huh?!"
- — Marty Santorelli
Marty was born in Empire Bay in 1933. His dad worked as a projectionist in the huge theater in Midtown, so Marty watched a lot of movies as a kid, especially gangster films. He dreamed of life in the mob, and in his teens took to hanging around Freddy's Bar, just like his childhood neighbor and role model, Joe Barbaro. He now runs errands for Joe - delivering messages, collecting his winning bets, and waxing his car. He nags Joe to let him come along on some of his jobs, but Joe sees Marty as a kid brother and too naive to get involved in serious business. 
Life of Crime
Marty works for the Empire Bay Cab & Co. as a taxi driver. While driving through the streets of Empire Bay looking for fares, a man suddenly jumped in front of Marty's cab, causing him to run over and kill him. Marty hid the body in the trunk, then asked Joe for help in disposing of it, which he did successfully at Bruski's Scrap & Salvage.
Shortly after that incident, Marty hit a parked car and a group of men showed up. After an exchange of words they opened fire, chasing him into the Kingston Subway Station, where he once again called on Joe to bail him out. By the time Joe arrived Marty was lying unconscious on the ground, and Joe managed to fight off the men and took Marty to El Greco for medical care.
In April of 1951 Marty was asked by Steve Coyne to come along as he met with Vito Scaletta and Joe Barbaro to take care of a problem with some Greasers. As the confrontation escalated into a gunfight, Marty returned the favor by saving Joe's life.
Several months later Joe asks Marty to be his getaway driver on an important job. While Joe wouldn't tell Marty exactly what the job entailed, they were planning to plant a bomb at the Empire Arms Hotel to kill Alberto Clemente. The job went horribly wrong, and as Clemente and his men were escaping the hotel, Marty was shot and killed in the parking garage as he waited for Joe and Vito to return.
- Skunk in the Trunk (Joe's Adventures)
- Saving Marty (Joe's Adventures)
- The Wild Ones
- Room Service (killed)
- Characters often find his high pitched voice annoying. Vito states it's "like Woody fuckin' Woodpecker" and Henry Tomasino claimed: "Kid's got a voice like fuckin' Minnie Mouse".
- A man resembling him is seen in the first cutscene of Home Sweet Home.
- In Chapter 10 Joe claims Marty was a great driver, yet both of his missions in Joe's Adventures were a result of him getting into car accidents.