Saint Nicholas

 was a Christian who was associated with Christmas.

Several Londoners in the 17th century attempted to conjure Saint Nicholas but instead conjured an alien who called himself "Saint Nick" and feasted on their belief in Christmas. (PROSE: The Feast)

The bones of Saint Nicholas were kept in a church in Myra. When they were stolen by sailors, the Second Doctor snuck on board their ship and replaced them with plastic ones. He then suggested to Victoria that they take the bones to the North Pole to bury them. (PROSE: Saint Nicholas's Bones)