Thallelaeus’s name day is May 20, the feast of Thalleleos the Unmercenary.
Churches that follow the Old (Julian) Calendar keep the same feast on June 2 of the civil calendar. See everything commemorated on May 20.
The saint behind the name
Thalleleos the Unmercenary
May 20, Martyr, Θαλλέλαιος ο Ανάργυρος
Thalleleos was a young physician from Lebanon who treated the sick without payment and led many to Christ. Arrested at Aegae in Cilicia under the Emperor Numerian, he was subjected to tortures which, tradition relates, turned back upon his tormentors.
Name days: Thalelaios, Thalleleos, Thaleleos, Thallelaeus
Also celebrating on May 20
These names share the feast, many of them other forms of the same name:
Thalelaios, Thalleleos, Thaleleos
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.