| Honorific Prefix: | Saint |
| Castor of Apt | |
| Birth Date: | 4th century |
| Death Date: | c. 420 |
| Feast Day: | 2 September |
| Birth Place: | Nîmes, France |
| Patronage: | Apt, France |
Castor of Apt (died) was a bishop of Apt, in Gaul.
He was born in Nîmes and may have been the brother of Leontius of Fréjus. Castor was a lawyer and married to a wealthy widow. He lived in Marseilles. His wife, however, allowed him to enter the religious life; she herself entered a nunnery. Castor founded the monastery of Manauque (Monanque) in Provence which followed the monastic rule of John Cassian. He was subsequently made bishop of Apt. [1] He died of natural causes.
John Cassian wrote the De institutis coenobiorum at the request of Castor.[2]
His feast day is September 2. His relics are still preserved in the cathedral of Apt, of which he is one of the patrons.