Santino 'Sonny' Corleone (1916-1948) is a fictional character in Mario Puzo's 1969 novel The Godfather(Film) and its 1972 film adaptation. He also appears as an infant, as a young boy, and an adult in The Godfather Part II.
In the novel and film,he is the oldest son of New York City Mafia Don Vito Corleone and Carmella Corleone. He has two brothers, Michael and Fredo, an adoptive brother, Tom Hagen, and a sister, Connie. Sonny was portrayed by James Caan in the film, who reprised his role for a flashback scene in Part II. Director Francis Ford Coppola's son Roman Coppola played Sonny as a boy in the 1920s scene of that film.Born in 1916, Sonny is the most impulsive and violent of Vito's children and, before Michael's rise to power, the most involved in his father's criminal operations. As the oldest child, he serves as a protector to his younger siblings. When Sonny was 16, he committed a robbery. His father learns about it from Peter Clemenza, who stood as godfather to Sonny. When Vito asks Sonny why he did this, Sonny tells him that he saw his father kill Don Fanucci back in 1920. He then tells his father, "I want to learn how to sell olive oil." Vito realizes what Sonny really means, and sends him to Clemenza for training. Sonny "made his bones" when he was 19.
Sonny eventually becomes a capo in his father's family, gaining a reputation as a ruthless killer. By the end of World War II, he has become his father's underboss and heir apparent. He is not without a softer side, however; at the age of 11, he meets a homeless boy, Tom Hagen, who thereafter lives with the family and becomes the family's consigliere. He also acts as a protector to his younger siblings, especially Connie. The book reveals that he secretly cannot bring himself to harm women or children, or anyone who can't defend themselves, which may be what saves his sister's husband, Carlo Rizzi.
Although Sonny has a wife, Sandra, and four children, he frequently cheats on Sandra with other women. At the time of the film, he has carried on a long-running affair with Lucy Mancini, who served as one of his sister's bridesmaids. The normal course of events in Sonny’s life is upturned when Virgil 'The Turk' Sollozzo comes to Don Vito with an offer of entering the drug business, backed by the Tattaglia family. Vito rejects the deal, although Sonny shows slight interest. Sollozzo responds by trying to assassinate Vito, in hopes that Sonny will take over the Family and go into the drug business.
The assassination attempt fails but leaves Vito near death, although he eventually recovers. Sonny takes over as acting boss and issues an ultimatum to the Tattaglias—turn over Sollozzo or face war. When he learns that Sollozzo instead had his father's top button man, Luca Brasi, killed, he orders Bruno Tattaglia, Don Philip Tattaglia's son, killed in response.
Michael, who had previously distanced himself from the family's criminal enterprise, volunteers to kill Sollozzo and his ally, police Captain McCluskey. Sonny is initially amused by this, believing Michael is taking McCluskey breaking his jaw the night before too personally, but Michael convinces him that it's in the family's best interest to kill Sollozzo and McCluskey ("It's not personal, it's strictly business."). Michael kills Sollozzo and McCluskey at Louis's Restaurant in the Bronx and is sent immediately to Sicily to wait out the inevitable crackdown on the Five Families.
In retaliation, during the spring of 1948, Tattaglia's partner, Don Emilio Barzini, enlists the help of Sonny's brother-in-law, Carlo Rizzi, in setting a trap for Sonny. Sonny had already given Carlo a savage beating upon learning that Carlo was abusing Connie, unintentionally revealing a weakness. To draw Sonny out into the open, a vengeful Rizzi inflicts a particularly vicious beating on Connie, who telephones Sonny, begging for help. In a fit of rage, Sonny speeds out of the family compound unaccompanied, and heads for Connie's apartment to confront Rizzi. As Sonny approaches a toll plaza, a number of Barzini's men emerge with Tommy Guns and brutally murder him. As a result, Don Corleone promises not to seek vengeance on the Barzini Family for his son's death in exchange for stepping down and Michael's safe return home. Later, Michael, who was not part of his father's promise, has all of his opponents assassinated and has Carlo garroted to death in revenge.
Ultimately the entire novel or the first part of the trilogy have major turns of events due to multiple mistakes of Sonny.
After Salvatore Maranzano got killed by Tessio regime in Bronx, this was an ultimate end of the Castellammarese War as well as was a decisive win for Family. After that, it was a peaceful empire for Corleones in next ten years up to 1946. After Solozzo came to don with the proposition, it was Santino who showed interest in drug business, under-estimating his father's will. He asked an impulsive question of Solozzo in the meeting and that was enough for Solozzo to understand that despite the Don and the Family, Santino was interested in his proposition. This made Solozzo feel that if he can outfight the Don, it might be possible for him to have Sonny in the deal. So, he attempted an assassination on the Don which although a failure brought a master stroke against the Family.
Again after the second attempt on Vito at the hospital, Sonny ran mad and sent Tessio's men to kill Bruno Tattaglia, underboss of the Tattaglia Family. Following this when Solozzo called on him for a truce, the family realized this was just an excuse for Solozzo to buy more time to take a breath and to prepare another, better-planned assassination on the Don. So in a Family meeting in Don's house at the Corleone Mall in Long Beach, Santino with his consigliere Tom Hagen and caporegimes Salvatore Tessio & Peter Clemenza, made the decision that Solozzo would have to be killed and that this would solve all the problems. Although this plan had nothing wrong with it , what was wrong was that Sonny approved Michael to shoot Solozzo and McCluskey. Although Michael was interested in shooting and also Tom Hagen didn't disapprove of it, as a Don Sonny wasn't very prudent here. Michael's shooting at them triggered the Five Families War of 1946 that came as a huge expense and loss of interest to the Family. After the shooting, Michael was sent hiding to Sicily. He was unable to come back for more than a year. This was very damaging to him because he couldn't stay beside his father to learn Family business. Michael's exile also tied Vito's hands from avenging Sonny's own assassination. After Sonny was assassinated as a result of Michael's action and to put a stop to the 1946 war, the Don had to make peace with the other families. He couldn't avenge his son's death because his major weakness was the exile of Michael. To bring Michael back, Corleone family unconditionally made peace with other families after Sonny's death, which was remarked as a surrender by the Don, though Hagen later stated that this move was a very cunning tactical retreat of Don Vito Corleone.
The beating of Carlo was Sonny's fatal mistake. On the day he'd beaten Carlo half to death, it was an obvious exposure of his weakness, which was noted and taken into account by his enemies. The fear of him being killed because of this weakness was shown by Tom Hagen, who was furious when he learned his brother had beaten Carlo on an open street. This error in judgment led directly to Sonny's death, it was exploited by Emilio Barzini to have him killed.