Thodoris’s name day is April 20, the feast of Theodore Trichinas.
Churches that follow the Old (Julian) Calendar keep the same feast on May 3 of the civil calendar. See everything commemorated on April 20.
The saint behind the name

Theodore Trichinas
April 20, Venerable, Θεόδωρος
St. Theodore Trichinas was born in Constantinople and embraced the monastic life in a monastery of the countryside. He is called Trichinas, the hair-shirt wearer, because his only garment throughout his long ascetic struggle was a rough covering of hair, worn in every season as he mortified the flesh through fasting, vigil, and cold.
Also celebrating on April 20
These names share the feast, many of them other forms of the same name:
What to say on a name day
The Greek wish is Χρόνια Πολλά (Chronia Polla), “many years.” A call or a short message on the day is what people remember. See name day wishes you can send and what a name day is.