- "This is a high risk business. If you don't like it, you can always go break your back working for peanuts down at the docks."
- — Henry Tomasino
Henry was born in 1911 and was one of seven sons of Silvio Tomasino, a Sicilian mobster. He was sent to America in 1931 by his father to escape Mussolini's crackdown on the Sicilian Mafia and because of his fear that he would either be drafted into the Army or imprisoned. Upon arriving in Empire Bay, Henry came under the protection of family friend and ruthless mob boss Alberto Clemente. Now a full member of the Clemente family, he is regarded as a loyal soldier and respected hitman. Henry is reserved and has few friends. His sole motivation is pride. 
Not much is really known about Henry because he didn't talk about himself or his life very often and he had few friends. He was very knowledgeable about the various criminal organizations in Empire Bay, but he was different from the other mobsters he worked with, being very level-headed, proper, and refined; he was an old fashioned man of honor.
Gas Stamp Heist
Henry is introduced to Vito Scaletta by Joe Barbaro in early February, 1945. In this meeting he recruits Vito to steal some gas stamps from the Office of Price Administration. Vito does so successfully, but Henry finds out that they expire the next day. He then tells Vito that he needs to sell the stamps to area gas stations before midnight.
The next day he asks Joe and Vito to rob a jewelry store owned by someone who owes money to Don Clemente. The robbery doesn't quite go according to plan, as Brian O'Neill and his gang also try to rob the store. After an intense shootout with them and the police, Vito and Joe escape with the jewelry.
Hit on Sidney Pen
A short time later, Henry is given a contract by Luca Gurino to kill Sidney Pen, and he enlists the help of Vito and Joe once again. While the job doesn't go exactly as planned, they manage to kill Pen, but Henry is severely injured when he is shot in the leg. Vito and Joe have to rush Henry to El Greco for medical care.
Less than a week later Vito Scaletta is arrested for the gas stamp heist Henry set up and is sentenced to ten years in prison. Along the way Joe Barbaro gets in trouble with Luca Gurino and Henry has to warn Joe about a contract out on him, forcing Joe to leave Empire Bay. Henry doesn't see either of them again for six years, when he notices them both in disguise at the Empire Arms Hotel just before Don Clemente's assassination.
Joining with Falcone
After the assassination of Alberto Clemente, Henry is out of work, so he meets with Vito and asks if he would vouch for him with the Falcone Crime Family; Vito does so gladly. Henry's first assignment is to kill Vinci Consigliere Leo Galante. The job is a bust but despite Leo escaping, Henry is still welcomed into the Falcone family.
The Drug Deal
Henry later convinces Joe and Vito to enter the drug trade with him. With the potential to make an easy $75,000 on the deal, they go to Bruno Levine, a loan shark who has ties to the Commission, to borrow the $35,000 they need. However, Bruno decides the loan is high risk and wants an additional $20,000 in return by Friday. Henry agrees and Bruno lends them the money.
The three then meet Triad enforcer Zhe Yun Wong to buy the heroin. The deal goes smoothly, but as they leave they're approached by some men masquerading as police officers, who try to take the drugs from them. Henry realizes they're not cops and a gunfight erupts. After they successfully deal with them, they spend the afternoon selling the drugs around Empire Bay, then celebrate with a night on the town.
At some point Henry Tomasino became an informant for the Federal Bureau of Narcotics. Whether he was an informant all along or became one at some other point is unclear, but he managed to supply the feds with enough information that many in Empire Bay were worried. When Mr. Wong found out about Tomasino through one of his contacts in the bureau, he took matters into his own hands.
On September 24, 1951, as Vito and Joe approach Lincoln Park to meet with Henry, they see him on the ground being attacked with meat cleavers by several Empire Bay Triads. Though Vito and Joe stop the attack, they're too late and Henry dies of his injuries.
After witnessing Henry's death, Vito and Joe follow Zhe Yun Wong to The Red Dragon restaurant. After killing all of his men, they confront Wong and demand their money and an explanation for killing Henry. Wong states that a contact told him Henry was an informant, but he refuses to say where the money is. Joe then shoots Wong in the head, killing him and avenging his role in Henry's death.
Two days later when meeting with Vito, Mr. Chu and Leo Galante confirm Wong's allegation, with Leo saying "He was working for the Feds! He was a fuckin' rat. That's why Mr. Chu's people did what they did." Carlo Falcone also confirms this when Vito confronts him at the Zavesky Observatory, blaming Vito for bringing a rat into his house.
- Silvio Tomasino (father, deceased)
- Eleonore Castrogiovanni (mother)
- Bettina Canavosio (wife, deceased)
- Basilio Tomasino (brother)
- Fausto Tomasino (brother)
- Manfredo Tomasino (brother)
- Osvaldo Tomasino (brother)
- Pietro Tomasino (brother)
- Salvatore Tomasino (brother)
- Enemy of the State
- Murphy's Law
- The Buzzsaw
- Room Service
- A Friend of Ours
- Sea Gift
- Exit the Dragon (Killed)
- Witness - Frozen Memories (Joe's Adventures)
- Henry was one of the "wiseguys" that Joe and Vito idolized when they were children.
- He frequents Freddy's Bar, which is the front of operations for the Clemente family.
- According to Frankie Potts' files, he has several addresses, but he mainly lives at the Empire Arms Hotel.
- He goes to church every Sunday, suggesting that he is a devout Catholic.
- Henry may be a distant relative of Frank Vinci, as Vinci's mother's maiden name is Tomasino.
- His thirteenth contract was to kill the "Fat Man". He believes this is the reason he got shot, as the number thirteen is associated with bad luck. Coincidentally, his death occurs in Chapter 13.
- One news report after his death says he was a struggling entrepreneur; another claims he had interests in waste disposal and construction.