Kelly Clarkson can cross another item off of her long list of accomplishments. Arguably the most famous ‘American Idol‘ alumna, Clarkson’s single ‘Stronger (What Doesn’t Kill You)’ off her album ‘Stronger’ became the best-selling ‘Idol’ single of all time, even knocking fellow ‘Idol’ winner Carrie Underwood back to second place. Underwood held the title when her single ‘Before He Cheats’ was released.