The de Barry family (de Barra/Barri) is a noble Cambro-Norman family which held extensive land holdings in Wales and Ireland. The founder of the de Barry family was a Norman knight, Odo, who assisted in the Norman Conquest of England and south-east Wales during the 11th century. As a reward for his military services, Odo was granted estates in Pembrokeshire and around Barry, Wales, including Barry Island just off the coast.
Odo's grandson, Gerald of Wales, a 12th-century scholar, gives the origin of his family's name, de Barry, in his Itinerarium Cambriae (1191): "Not far from Caerdyf is a small island situated near the shore of the Severn, called Barri, from St. Baroc ... From hence a noble family, of the maritime parts of South Wales, who owned this island and the adjoining estates, received the name of de Barri."
Many family members later assisted in the Norman invasion of Ireland. For the family's services, King John of England awarded Philip's son, William de Barry, extensive baronies in the Kingdom of South Munster, specifically the defunct Uí Liatháin kingdom (O'Lethan and Imokilly) with its late seat at Castlelyons.