Kara DioGuardi is a singer-songwriter, record producer, music publisher, A&R executive, and TV personality. And as of 2009, she was added as a fourth judge on American Idol.

DioGuardi voiced herself alongside Idol host Ryan Seacrest, and fellow judges Randy Jackson, Ellen DeGeneres, and Simon Cowell.

Guest stars in Season 21

Mitch AlbomAngela BassettWren T. BrownNeve CampbellKim CattrallSacha Baron CohenBob CostasSimon CowellEllen DeGeneresKara DioGuardiAnne HathawayJonah HillEddie IzzardRandy JacksonEartha KittGary LarsonChuck LiddellCooper ManningEli ManningPeyton ManningChris MartinJackie MasonJordan NagaiYael NaimSeth RogenRyan SeacrestSarah SilvermanSmothers Brothers

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