STAGE TUBE: Megan Mullally Serenades Justin Beiber!

Megan Mullally stopped by the Ellen Degeneres Show and serenaded Justin Beiber for his 18th birthday. She sang him her version of  "Fever" which she appropriately changed to "Beiber." Check out the performance below!

Megan Mullally made her television debut alongside Elaine Stritch and Ellen Burstyn on "The Ellen Burstyn Show" in 1986. She appeared opposite Stanley Tucci as Walter Winchell's wife in Paul Mazursky's award-winning HBO bio-pic Winchell and opposite Juliet Stevenson in Lifetime's "The Pact." She is best known for her two-time Emmy and four-time SAG Award-winning role as Karen Walker on the hit NBC Series "Will & Grace.

She has received an Outer Critics Circle Award nomination for her performance as Rosemary in the Broadway revival of How to Succeed In Business Without Really Trying opposite Matthew Broderick and starred in the hit Broadway musical, Young Frankenstein. Her other Los Angeles theater credits include The Berlin Circle at The Evidence Room Theater, for which she won the 2000 BackStage West Garland Award for Best Lead Actress in a Play and the L.A. Weekly Award for Best Leading Female Performance. She also appeared in Mayhem at The Evidence Room, as well as a variety of plays and musicals in both Chicago and Los Angeles.