Atanas’s name day is January 18, the feast of Athanasios the Great.
Churches that follow the Old (Julian) Calendar keep the same feast on January 31 of the civil calendar. See everything commemorated on January 18.
The saint 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
Also celebrating on January 18
These names share the feast, many of them other forms of the same name:
Athanasios, Thanassis, Thanos, Nasis, Athanasius, Thanasis, 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.