Marcello’s name day is December 29, the feast of Marcellus of the Unsleeping Ones.
Churches that follow the Old (Julian) Calendar keep the same feast on January 11 of the civil calendar. See everything commemorated on December 29.
The saint behind the name
Marcellus of the Unsleeping Ones
December 29, Venerable, Μάρκελλος
Venerable Marcellus was born in Apamea in Syria in the fifth century and became a monk of the monastery of the Akoimetoi, the Unsleeping Ones, near Constantinople, where the praise of God was sung without ceasing day and night. Chosen abbot, he governed the brotherhood with wisdom and took part in the struggles of the Church for the Orthodox faith. He reposed in peace.
Also celebrating on December 29
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.