20 Years After Ruben Studdard and Clay Aiken Faced Off on ‘American Idol,’ the Two Reunite for ‘Nostalgia’ Tour, Season 21 Finale

Keith Urban Is Returning to 'American Idol' as a Guest Mentor

Keith Urban to Return to ‘American Idol’ as Season 21 Finale Mentor: Exclusive

American Idol fans call for Alanis Morissette to 'permanently' replace Katy Perry as a judge