John of Procida (prō´chēdä), c.1225–c.1302, Italian conspirator, lord of the island of Procida. He was an ardent supporter of the Hohenstaufen cause in Sicily and attempted to secure the island for Manfred and Conradin against the claims of Charles of Anjou, who was given Sicily by the pope. After Manfred's defeat and Conradin's execution (1268) by Charles, John went into exile at the court of Manfred's son-in-law, Peter III of Aragón. Peter sent him to seek the aid of the Byzantine emperor, Michael VIII, for a projected invasion of Sicily. John probably also secretly visited Sicily, preparing the great uprising of the Sicilian Vespers (1282) against Charles, which ultimately brought Peter to the Sicilian throne. In 1283, John was made chancellor of Sicily.

John of Procida: see John of Procida.