Joseph 'Joe' Valachi (September 22, 1903 - April 3, 1971) was the first person to acknowledge the existence of the mafia. He is also the person who made La Cosa Nostra a household name. In October of 1963, he testified before John L. McClellan's congressional committee that the mafia did exist. The effect of this was devastating for the mob. After his testimony, the mob was no longer invisible to the public eye.
He memoirs were published as the Valachi Papers, which were later turned into a movie by the same name.
Valachi died in 1971 at La Tuna Federal Correctional Institution in Texas.