Mariah Carey is many things – but casual isn't one of them. So naturally, when she performed Sunday (Oct. 6) evening at the American Music Awards 50th Anniversary Special, she had to make an entrance.

For years, Mariah Carey has reigned as the Queen of Christmas. With that unsnatchable crown, the 56-year-old diva has seemed perfectly content to chill until defrosting herself right after Halloween ...