- "I mixed some vegetable oil in it, makes the gasoline thick, sticky. We're just gonna let it soak in a little bit, work its way into every nook and cranny."
- — Tommy Marcano
While his brothers Sal, Lou and Lucio were at a State Penitentiary at Cordoba, Tommy was on elementary school and repeating one year due to being a delinquent and troublemaker, though he was still very clever and smart. By the time he finished high school, the Marcanos were already in charge of the city's criminal underworld.
With their immense power and wealth, Sal told Tommy to go to college, get a good degree and become a respected lawyer in some big agency. However, Tommy disagreed and wanted to enter the family's businesses. Sal agreed, and put him in charge of their casinos, rackets and operations in Havana, Cuba. Aided by older mobster Frank Pagani, Tommy successfully managed to administrate the family's businesses in Cuba, but when Castro took over, his soldiers cracked down on the mob in Havana and sent a hit squad against Tommy. Tommy only survived due to Pagani's efforts, who managed to smuggle him and his money out of Cuba safely.
When he arrived in New Bordeaux from Cuba, Tommy demanded that the Southdowns district be handed over to him, and Sal eagerly collaborated, also rewarding Pagani with Tickfaw Harbor for getting Tommy out of Cuba in one piece. Tommy managed to keep the Rackets in the Southdowns discreet and out of the public eye, putting his two men Johnny Peralta and Artie Higgins of the gambling and black market rackets in the district.
Tommy also owned The Acadia boxing gym in Southdowns and used it as one of his fronts, while also organizing a league and putting effort onto it. He used a chain of agents to recruit fighters for his "Jungle Fights", Alcee Bennett was one of those.
In 1968, Pagani's rackets around Tickfaw were dismantled by Lincoln Clay while Pagani was in Havana taking care of the smuggling businesses. Tommy called Pagani to inform him of the situation, telling him to return to Tickfaw to clean up the mess, and though Pagani was angry at first, he agreed. In the end, Pagani ended up killed by Lincoln and Tickfaw was now far from the Marcanos' grasp.
Tommy hired a Cuban counterfeiter named Alvarez to help them print the money using the money plates Sal stole from the Federal Reserve shortly before the massacre against the Black Mob. Lincoln then moved on to take over Southdowns from Tommy, dismantling his two rackets and scaring Alvarez enough that he tried to flee the country with his uncle Zarraga. However, Zarraga ratted Alvarez to Tommy, who sent a squad to pick up Alvarez or kill him if he doesn't collaborates. Alvarez is rescued by Lincoln though.
Tommy then goes to Sal's office to explain him that the situation got out of control, and Sal lectures him and after some discussion, sends him to the Acadia in order to protect the money plates from Lincoln. Lincoln infiltrated the gym with Alcee's help and pretended to be another boxer, winning all of the rounds and then meeting Tommy face-to-face for his victory. Tommy recognized the trick however, and had his men knock Lincoln out and bring him to the upper floors of the gym.
There, Tommy had Lincoln tied in a chair, and covered him with customized gasoline, saying that when he lights it up, it's "going to burn like napalm". Making some remarks about how he's going to die slowly, this gave Lincoln time to cut the ropes tying his wrist and shoot Tommy's men and wound him. While Lincoln splashed gasoline around the room and took the money plates, Tommy explained that Sal had told him to go to law school and work for some big agency, "do something decent with his life". When Lincoln told him he should have listened to Sal, Tommy replied that "it's in the blood", and Lincoln agreed, saying that he is who he is, and there is no point in trying to change that.
Tommy insulted Lincoln one last time, before the latter lighted a lighter and threw it on the gasoline around the room, making it burn. Tommy looked at Lincoln with a shocked look, shouting that he can't go out like this. Lincoln told him that he didn't need to worry to be alone in hell, saying that his brothers will come along shortly. Lincoln left him to die, and Tommy was burned to death in the inferno that destroyed his boxing gym.
- Sal Marcano (brother, deceased)
- Lou Marcano (brother, deceased)
- Giorgi Marcano (nephew, deceased)
- Olivia Marcano (sister-in-law, deceased)
- Lucio Marcano (brother, deceased)
- Michael Grecco (nephew, deceased)
- Valerio Marcano (father, deceased)
- Virginia Marcano (sister-in-law)
- His older brother Sal seemed to genuinely adore Tommy, holding him in high regard and saying that he was a "smart kid" after Tommy was killed. If Tommy is the last target killed before Sal Marcano himself, Sal is almost on the verge of tears in the cut scene.
- It is possible to perform a knife execution on Tommy before he burns alive or simply shoot him instead of letting him to die in the fire. He can also be killed with grenades and other throwables.
- Tommy is the youngest of the Marcano brothers. This is likely a large part of what hurts Sal emotionally about his baby brother's demise.