Anthelm of Belley was a 12th-century Carthusian prior and Catholic bishop. Born in Chignin around 1107, he initially held an ecclesiastical position before joining the Carthusian Order at Portes at age thirty. He eventually became the prior of the Grande Chartreuse, where he served as an influential administrator for many years. Later in life, he was appointed the bishop of Belley by Pope Alexander III. Known for his uncompromising nature, he was a dedicated reformer who sought to improve both his monastic order and his diocese.