Here are the Russian Orthodox Saints that start with a "C," with their feastdays where available:
- Caesaria, In Palestine, Eight Martyrs of, March 24
- Carterius of Palestine, November 5
- Cassian the Anchorite of the Far Caves, February 29
- Castorus of Palestine, November 5
- Catherine of Alexandria, November 24 and 25
- Celsus, January 8
- Censorinus, January 30
- Charalambos the Wonderworker, February 10
- Charatina, Abbess of Novgorod, October 5
- Chariton, September 28
- Christodoulos of Kassandra, July 28
- Chionia, Agapia, and Irina the Martyrs
- Christina the Martyr
- Christodoulos of Kassandra, July 28
- Christofer, May 22
- Christopher of Adrianople, April 16
- Christos the Gardener, February 12
- Christos of Ioannina, August 15
- Chrysanthus, March 19
- Chryse, January 30
- Chryse Zlata, October 13
- Claudius, March 19
- Clement, Pope of Rome, November 25
- Conon the Gardener, March 5
- Conon of Penthoucla, February 19
- Constantine the Great, May 21
- Constantine of the Hagarenes, June 2
- Constantius the Russian, December 26
- Coprius of Palestine, September 24
- Cornelius of Komel, May 19
- Cosmas of Aetolia, August 24
- Cosmas of Birsk, November 12
- Cosmas the Poet, October 14
- Cosmas, Damian, and Leontius the Martyrs
- Cuthbert, October 26
- Cyprian the Former Magician, October 2
- Cyprian the New Monk, July 5
- Cyprian of Suzdal, October 2
- Cyriacus the Anchorite, September 29
- Cyriacus, Patriarch of Jerusalem, October 28
- Cyril, Archbishop of Alexandria, January 18
- Cyril, Archbishop of Jerusalem, March 18
- Cyril and Methodius
- Cyril of Belozersk, June 9
- Cyril of Pythion, April 18
- Cyril of Velsk, June 9
Source: http://www.gnisios.narod.ru/lives.html