Guarinus of Sitten was a 12th-century Benedictine monk who served as the Bishop of Sion. Born into a noble family in Pont-à-Mousson around 1065, he entered the Molesme Abbey as a monk in approximately 1085. He later played a central role in establishing Aulps Abbey in Savoy, where he served as the second abbot. His ecclesiastical career culminated in his appointment as bishop in 1138, a position he held until his death in 1150.