Long before Meghan Markle came onto the scene, there were only two Americans the world regarded as royalty: Mariah Carey and Britney Spears. The pop princesses ruled the '90s. Carey wowed fans with her incredible range in hits like "Always Be My Baby" and her eternal hit, "All I Want for Christmas Is You." Meanwhile, Spears won over hearts young and old alike with her school-girl-gone-bad persona in songs like "...Baby One More Time" and (You Drive Me) Crazy." And while they could have been competitive frenemies, they totally fangirled over each other.