Sollozzo (Al Lettieri) is one of the main villains in the movie. He represents the future wave of criminal activity—drugs. He's the worst kind of pusher, dealing with poppy growers in Turkey in order to control the supply of heroin in America (leading to his nickname "The Turk").
When the Godfather refuses to do business with him and lend his political connections to prop up the heroin trade, Sollozzo, with the aid of the Tattaglia family and (secretly) Don Barzini, goes all-out.
He sends Luca Brasi to sleep with the fishes and orders an assassination attempt on Don Corleone, who miraculously survives. However, Sollozzo gets his: Michael Corleone kills him, along with Captain McCluskey, in the middle of dinner at an Italian restaurant in the Bronx.