Palladius, Saint (pəlāˈdēəs) [key], d. 431, first bishop of Ireland. Probably of Gallo-Roman origin, Palladius was sent (431) by Pope Celestine I to proselytize among the Irish. He built three churches but met with much opposition and left the same year. He is the forerunner of St. Patrick, who succeeded him in his work. Feast: July 7.