| Patriarch Of: | Ecumenical Patriarch of Constantinople |
| Enthroned: | 607 |
| Ended: | 610 |
| Religion: | Chalcedonian Christianity |
Thomas I (Greek: Θωμᾶς; died 21 March 610) was the Ecumenical Patriarch of Constantinople from 607 to 610. He has been canonized a saint in the Eastern Orthodox Church. His feast day is 21 March for those churches which follow the Julian Calendar, 21 March falls on 3 April of the modern Gregorian Calendar).