"White Christmas" is actually the best-selling physical single of all time, according to the Guinness Book of World Records? Just counting Crosby's version, the song has sold over 50 million copies worldwide. Including other artists' covers, there are over 100 million copies.

While Andy Williams is known for his holiday hit "It's the Most Wonderful Time of the Year," his record company insisted on his cover of "White Christmas" being the album's single.

The song "Feliz Navidad" actually came out in 1970. "Feliz Navidad" is one of the most-downloaded and most-aired Christmas songs of all time, but it only came to prominence in 1998. For its first 20+ years, it remained a fairly niche track.

Dan Fogelberg's "Same Old Lang Syne" has been contested as being either a Christmas song (based on the lyrics) or a New Year's song (based on the title). However, it actually peaked in popularity in late February 1981.