Monoculus is a genus of succulent plants.
Monoculus (Latin for "one-eyed") may also refer to:
John fitzRichard (), Anglo-Norman nobleman nicknamed Monoculus Otto II, Duke of Brunswick-Göttingen (c. 1380–1463), nicknamed Monoculus Raymond IV, Count of Toulouse (c. 1041–1105), nicknamed Monoculus Peter Monoculus (died 1185), Cistercian abbot Monoculus, the journal of the World Association of Copepodologists
See also List of people known as the One-Eyed