September 7, 1940 – January 10, 1983) was an American mobster in the Gambino crime family in New York City. He headed a group known as the "DeMeo crew", which consisted of approximately 60 members involved in murder, bombing, torture, contract killing, arson, extortion, loan sharking, car theft, hijacking, drug trafficking, weapons trafficking, prostitution and pornography. The DeMeo crew became highly notorious for the large number of murders they committed and for the grisly way they disposed of the bodies, which became known as "the Gemini Method". The crew is believed to be responsible for up to 1,000 murders, many of which were committed by DeMeo himself. DeMeo claimed that he single-handedly killed over 100 people, and stated he has killed with guns, knives, bombs, cyanide poisoning, strangulation, torture, decapitation, dismemberment, and setting people on fire. His extremely ruthless and brutal methods of killing people has made DeMeo one of the most dangerous and feared mobsters in New York. DeMeo was widely known for being a vicious killer and a very efficient hitman and served as one of Paul Castellano's chief enforcers and veteran executioners. Many mobsters called Roy "the one-man army", "The Devil himself" or "Paul Castellano's beast". DeMeo was greatly feared by everyone who knew him or heared of him, even some of the most ruthless mobsters was afraid of DeMeo. was later murdered in 1983 on the orders from Gambino crime family boss Paul Castellano.
Sammy "the Bull" Gravano once said of DeMeo in a 2023 interview, "Roy scared the scary guys. He was a fucking ferocious beast. Everyone was scared to death of him. Even John Gotti was afraid of him. He was a fucking killing machine. He loved and enjoyed killing people. He killed for business and pleasure. He killed in every way you could think of. He killed with guns, knives, bombs, setting people on fire, choking them with piano wire, poisoning their drinks or food, torturing the to death, cutting their fucking heads off... all he did was kill, kill, kill. He killed a'lot of fucking people. He could scare the Devil himself."