Cumméne Fota or Cummian (fl. c. 591- 12 November 661 or 662) was an Irish bishop.
Cummian was an Irish Bishop and fer léignid (Lector) of Cluain Ferta Brénainn (Clonfert), was an important theological writer in the early to mid 7th century. He is famous for a Paschal letter which displays his high level of learning. It consists of five manuscript folios, contains quotes from the Vulgate and Vetus Latina Bible; patristic commentary by Augustine, Jerome, Cyprian, Origen, Ambrosiaster and Gregory the Great; extracts from Canon law, ecclesiastical history and synodal decrees from Nicea and Arles in their original, uncontaminated forms, in addition to a decretum that enjoined on the Irish that, if all else failed, they should take their problems to Rome.
Cummian also owned - among a library of at least forty manuscripts - ten Paschal tracts including one he attributed to "santus Patricius, papa noster" and possibly a letter of Pelagius. He may have written a computistical manual, and a commentary on Mark. As Cummianus Longus he may be the author of a penitential, and a hymn on the apostles.
In 1162 his relics, along with those of Bishop Maeinenn of Clonfert "were removed from the earth by the clergy of Brenainn, and they were enclosed in a protecting shrine."
He is said to have been a foster-son of Saint Ita.