Pius I was the bishop of Rome from c. 140 to his death c. 154, according to the Annuario Pontificio. His dates are listed as 142 or 146 to 157 or 161, respectively. He is considered to have opposed both the Valentinians and Gnostics during his papacy. He is considered a saint by the Catholic Church with a feast day on 11 July, but it is unclear if he died as a martyr.