Clarence Ray Allen (January 16, 1930 – January 17, 2006) was an American criminal who was executed in 2006 at the age of 76 by lethal injection at San Quentin State Prison in California for the murders of three people. Allen was the second-oldest inmate at the time to be executed in the United States since 1976. Allen was already serving a life sentence for one murder when he was convicted of organizing the killing of three more people from prison, including a witness who had testified against him.