Saint Pedro Calungsod (Latin: Petrus Calungsod, Italian: Pietro Calungsod; (July 21, 1654 – April 2, 1672), also known as Peter Calungsod and Pedro Calonsor, was a Roman Catholic Filipino migrant, sacristan and missionary catechist who, along with the Spanish Jesuit missionary Diego Luis de San Vitores, suffered religious persecution and martyrdom in Guam for their missionary work in 1672.While in Guam, Calungsod preached Christianity to the Chamorro people through catechism, while baptizing infants, children and adults at the risk and expense of being persecuted and eventually murdered.