Pierre de Castelnau was a French Cistercian monk and papal legate active during the late 12th and early 13th centuries. Born in the diocese of Montpellier, he served as the archdeacon of Maguelonne before being appointed by Pope Innocent III in 1199 to combat the Cathar heresy. After joining the Cistercian order at the Fontfroide abbey, he acted as a chief inquisitor in regions including Languedoc, Viviers, and Montpellier. His life ended abruptly in 1208 following an assassination in the Rhone valley or Provence.
Life and death
While serving as a diplomat and inquisitor, Pierre became caught in political conflicts involving the count of Baux and Raymond VI, the Count of Toulouse. He was murdered on 15 January 1208, an event potentially carried out by an agent of Raymond. Although the killer's identity remained unproven, the Pope blamed the Count of Toulouse for the death, leading to his excommunication and the initiation of the Albigensian Crusade.
Veneration
Following his death, Pierre was beatified by Pope Innocent III in 1208. He is commemorated in the Catholic tradition, with his feast day observed on 15 January. His remains are kept within the church of the former Abbey of Saint-Gilles.