Peter Monoculus (died 29 October 1185) was a Cistercian monk who served as the abbot of Igny (1169–1179) and Clairvaux (1179–1185).
While he was abbot of Valroy he was struck by a serious disease that caused him the loss of one eye, hence his nickname, monoculus, 'the one-eyed'.
In 1180, he was conducting his visitation of Trois-Fontaines Abbey when Abbot Alard was murdered in the church by one of the monks.
He is today regarded as beatified and his reputed miracles are listed in the Acta Sanctorum.
Some of his stories were incorporated into the Old Icelandic Maríu saga under the heading "Af Pétro Clarevallensis".