Here are the Russian Orthodox saints that start with the letter "T," with their feastdays where possible:
- Taisia of Egypt
- Tamara the queen of Georgia
- Tatiana the Martyr of Rome
- Terence the Wonderworker, October 28
- Thea of Caesarea, July 16 and 18
- Thekla of Palestine, August 19
- Theoclitus the New Hieromartyr, April 18
- Theoclista of Lesbos, November 9
- Theoclistus, September 3
- Theodora of Sihla
- Theodore Stratilates
- Theodore the Branded, December 27
- Theodore of Edessa
- Theodore of the Kiev Caves, August 11
- Theodore of Lesbos, Bright Tuesday
- Theodore-Hatzi of Mytilene, January 30
- Theodore of Novgorod, January 19
- Theodore, Prince of Ostrog, August 11
- Theodore of Sykeon, May 5
- Theodore the Hesychast of the Far Caves, February 17
- Theodore the Boyar
- Theodore the Tyro, February 17
- Theodore, Schema-monk
- Theodosia, Virgin-Martyr, April 2 and May 29
- Theodosia of Constantinople, May 29
- Theodosius the Coenobiarch, January 11
- Theodosius the Great, January 17
- Theodosy of the Kiev Caves, May 3 and August 14
- Theodota, January 2
- Theodotus of Caesarea, September 2
- Theodolus, February 4
- Theodolus, January 14
- Theonas of Nicomedia, January 5
- Theopemptus of Nicomedia, January 5
- Theophanes the Branded, October 11
- Theophanes the Merciful, September 29
- Theophanes the New, August 19
- Theophanes the New Martyr, June 8
- Theophil of the Far Caves, October 26
- Theophilus of Palestine, November 5
- Theophilos of Zakinthos, July 24
- Theosebia the Deaconess, January 10
- Theotimus, September 4
- Theotimus of Palestine, November 5
- Thirty-Three Holy Martyrs of Palestine, August 16
- Thomais of Alexandria, April 13 and 14
- Thomais of Lesbos, January 3
- Thomas the Apostle, October 6
- Thomas of Maleon, July 7
- Thomas of Syria, April 24
- Three Virgins of Palestine, November 5
- Tikhon of Enisey, July 24
- Tikhon the New Martyr
- Tikhon of Zadonsk, August 13
- Timolaus, March 11
- Timothy of the 70 Apostles, January 22
- Timothy of Esphigmenou, January 22
- Timothy of Euripus, August 16
- Timothy of Palestine, November 5
- Titus of the 70 Apostles, August 25
- Titus the Presbyter of the Kiev Caves, February 27
- Titus the Warrior of the Far Caves, February 27
- Triandaphyllos the Seaman, August 8
- Tryphon, February 1
- Tryphon of Vyatka, October 8
- Twenty-Six Holy Martyrs of Zographou, October 10
- Two Martyrs of Ascalon, April 6
Source: http://www.gnisios.narod.ru/lives.html