Saint Domninus of Fidenza is an Italian Catholic saint. According to tradition, he died in 304 AD and was a native of Parma. The cathedral at Fidenza is dedicated to him. The Hieronymian Martyrology commemorates Domninus, but does not include any further information about him, and his feast day is cited as occurring on October 9. He is not commemorated in the martyrologies of Bede, Ado, Notker, or the Parvum Romanum.
His legend states that Domninus was Chamberlain to Emperor Maximian and keeper of the royal crown, and converted to Christianity, thereby incurring the emperor's wrath. Pursued by imperial forces, he rode through Piacenza holding a cross. He was caught and beheaded on the banks of the Stirone, outside of Fidenza, or the Via Aemilia. It is recounted that Domninus picked up his severed head and placed it on the future site of the cathedral of San Donnino.