The Duke of Castlebury is a character in A Princess for Christmas. He disowned his son, Charles when he married a commoner, but some time after the deaths of Charles and his wife, the Duke invites his grandchildren, Milo and Maddie, alongside their aunt and guardian, Jules Daly, to spend Christmas at Castlebury.
The Duke is a distant and unsociable man, and doesn't like the traditional Christmas celebrations, but the visitors (specially Maddie) manage to warm his heart.