O Come, All Ye Faithful
It is not known who wrote the music and words. Many people thought that it was written in the 15th or 16th century. However, this is not true. It was first written down in the 18th century by John Francis Wade, an English Roman Catholic. The music may have been taken from the a French opera called Le Comte d'Acajou. In the opera, there is an aria with a melody like the carol.