"Let's Be Bad" is an original song introduced in the fifth episode of the first season of the musical TV series Smash, entitled "Let's Be Bad". It was written by Marc Shaiman and Scott Wittman, but within the show's universe, it was written by the songwriting team Tom Levitt (Christian Borle) and Julia Houston (Debra Messing) for the Bombshell musical they are working on about Marilyn Monroe. The song was initially released as a single on iTunes and Amazon.com's MP3 store and is currently available as a track on the cast albums The Music of Smash and Bombshell.