Today’s saint comes from Ireland, but was martyred elsewhere St. Dymphna:
Saint Dymphna (also: Dympna, Dimpna, Damhnait, Damnat, from Gaelic Damh=stag and ait=little, i.e. “fawn”.) is a Christian saint. According to the Christian tradition, she lived in the 7th century and was the daughter of a pagan Irish king and his Christian wife. She was murdered by her father. The story of St. Dymphna was first recorded in the thirteenth century by a canon of the Church of St. Aubert at Cambrai, commissioned by the Bishop of Cambrai, Guy I (1238–1247). The author expressly stated that his writings were based upon a longstanding oral tradition and a persuasive history of inexplicable and miraculous healings of the mentally ill.
More can be found out about her at her wiki, located here.