'American Idol' is now in its 13th season on Fox. The show has made stars out of past winners like Kelly Clarkson, Jordin Sparks and David Cook. Even some of the contestants that didn't win have ended up with successful careers in music. Besides the contestants on the show, the series is also well known for its celebrity judges. For many years, 'America Idol' had a stable roster of the three original judges, but the lineup has changed more frequently in recent seasons. Who has been your favorite 'American Idol' judge?