Kelly Clarkson

Not only does this diva have the distinction of being the very first American Idol winner, she's also been far more successful than any of her successors so far. With her powerhouse vocals and down-to-earth charm, Clarkson literally became an overnight sensation on AI in 2002. Despite an embarrassing big-screen debut in the lambasted movie musical Justin to Kelly (which she was contractually obligated to star in opposite runner-up Justin Guarini), Clarkson made 2003 her year, with her best-selling debut album Thankful spawning a number of hit singles. Her 2004 follow-up, Breakaway (note those telling titles), was also a smash and earned the Grammy for Best Pop Vocal Album.