Still the most successful American Idol alum, Kelly Clarkson unleashed her vocal prowess during the first season of the hit TV show. She still holds the Billboard record for biggest jump to No. 1 with her hit single "My Life Would Suck Without You," and has had three of her albums debut at No. 1. Widely regarded as having one of the strongest voices in pop music, she's known for both the technical expertise and range of her vocals. Clarkson will forever be the poster child for reality TV success, one of the few performers to carve a legitimate career with longevity.