Salvatore „Sammy the Bull” Gravano (born March 12, 1945) is a former underboss of the Gambino crime family. He is known as the man who helped bring down John Gotti, the family’s boss, by agreeing to become an FBI informant. Originally a mobster for the Colombo crime family, and later for the Brooklyn faction of the Gambinos, Gravano was part of the group that murdered Gambino boss Paul Castellano. Gravano played a key role in planning and executing Castellano’s murder, along with John Gotti, Angelo Ruggiero, Frank DeCicco, and Joseph Armone. After Castellano’s death, Gotti elevated Gravano to underboss, a position he held at the time he became a government witness. At the time, Gravano was the highest-ranking member of the Five Families to break his blood oath and cooperate with the government, as well as the second confessed underboss of an American crime family to turn informer. His testimony drew a wave of Cosa Nostra members to also become government witnesses.