Carlo Digilio, also known as Zio Otto (7 May 1937 - 12 December 2005), was an Italian terrorist, soldier, and self-styled secret agent. He belonged to the neo-fascist group "Ordine Nuovo" and later became a collaborator. At the end of the first-degree process, he was convicted for the Piazza Fontana bombing, but the reliefs of law extinguished his guilt. He was also involved in the Piazza della Loggia bombing.