Most people named Thanasis keep their name day on January 18, the feast of Athanasios the Great. The Orthodox calendar has 1 other feast for the name.
Every feast on which Thanasis is celebrated
| New Calendar | Feast | Old Calendar (civil date) |
|---|---|---|
| January 18 | Athanasios the Great | January 31 |
| February 22 | Athanasius the Confessor | March 7 |
The saints behind the name
Athanasios the Great
January 18, Hierarch, Αθανάσιος ο Μέγας
St. Athanasios the Great, Archbishop of Alexandria, was born about the year 297 and as a young deacon accompanied his bishop to the First Ecumenical Council at Nicaea, where he stood against Arius in defense of the divinity of Christ. Made bishop of Alexandria in 328, he was driven into exile five times by Arian emperors yet never yielded, so that it was said of him: Athanasius against the world.
Name days: Athanasios, Thanassis, Thanos, Nasis, Atanas, Athanasius, Thanasis, Thanasi, Athanasis, Athanasia, Nasia, Sia

Athanasius the Confessor
February 22, Venerable, Αθανάσιος
St. Athanasius the Confessor was a monk who lived in the time of the iconoclast persecutions, when the emperors made war upon the holy images. For his steadfast veneration of the icons of Christ and His saints he endured affliction and persecution, bearing witness to the Orthodox faith without wavering.
Name days: Athanasios, Thanasis, Athanasius
Also celebrating on January 18
These names share the feast, many of them other forms of the same name:
Athanasios, Thanassis, Thanos, Nasis, Atanas, Athanasius, Thanasi, Athanasis, Athanasia, Nasia, Sia
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.