All I Want For Christmas Is You has been a holiday classic for 25 years - which means that a lot of people like to do their own versions of it. So here, along with Mariah's original version, are 12 covers of the song. Ironically, Mariah is actually in 3 of them - with Justin Beeber, Jimmy Fallon on The Tonight Show, and with James Corden on Carpool Karaoke.