Opportuna of Montreuil was an 8th-century Frankish Benedictine nun who served as an abbess. Born in Exmes, she entered the monastery at Monasteriolum, which was located near Almenêches. Following the leadership of her cousin, Lantildis, she rose to the position of abbess. She was the sister of Chrodegang, the Bishop of Séez. Her life concluded in 770 at Montreuil-au-Houlme, shortly after her brother was murdered.