When I was young, one of our priests actually made his entrance into the sanctuary once to the strains of Here Comes Santa Claus.
More recently, at a Byzantine Rite church, when the sixth of December fell on a Sunday, after Divine Liturgy, a mysterious figure in bishop's robes made his way in to the church and led the children of all ages present in a prayer, before handing out small trinkets.
Saint Nicholas is, (Greek, Άγιος Νικόλαος , Agios Nikolaos, "victory of the people") is the common name for Nicholas of Myra, a Lycian saint and Bishop of Myra in Lycia of Anatolia (modern-day Antalya province, Turkey). Because of the many miracles attributed to his intercessions, he is also known as Saint Nicholas the Wonderworker. He had a reputation for secret gift-giving, such as putting coins in the shoes of those who left them out for him, and is now commonly identified with Santa Claus. His reputation evolved among the faithful, as was the custom in his time. In 1087, his relics were furtively translated to Bari in southern Italy. For this reason, he is also known as Saint Nicholas of Bari.
I like the idea of his relics being transported "furtively". At night while most slept, perhaps? were there entrances and egresses by chimney involved?