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 a FBI informant.
Originally a mobster for the Colombo crime family, and later for the Brooklyn faction of the Gambinos, Gravano participated in the conspiracy to murder Gambino boss Paul Castellano. Gravano played a key role in planning and executing Castellano’s murder; other conspirators included 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 Cosa Nostra oath and cooperate with the government. His testimony drew a wave of Cosa Nostra members to also become government witnesses.