Hilary of Poitiers (c. 300 – c. 368) was Bishop of Poitiers and is a Doctor of the Church. He was sometimes referred to as the "Hammer of the Arians" (Latin: Malleus Arianorum) and the "Athanasius of the West." His name comes from the Greek word for happy or cheerful. His optional memorial in the Roman Catholic calendar of saints is 13 January. In the past, when this date was occupied by the Octave Day of the Epiphany, his feast day was moved to 14 January.