Hilty joins the previously announced Debra Messing, who will play Julia, the lyricist for a musical about Marilyn Monroe. Hilty will play an actress who acts out scenes from the show as they develop. The role of the show's composer, Tom, has not yet been cast.

Hilty has appeared on Broadway in 9 to 5 and Wicked. Messing, an Emmy winner for "Will and Grace," appeared in the Manhattan Theatre Club productions of Collected Stories and Three Dogs and a Bone, and in the WPA production of The Naked Truth. She recently starred in the USA series "The Starter Wife."

The pilot episode of "Smash" was written by playwright Theresa Rebeck (Mauritius, The Scene) and will be directed by Tony Award winner Michael Mayer (American Idiot, Spring Awakening).

Tony Award winners Marc Shaiman and Scott Wittman (Catch Me If You Can, Hairspray) will write songs for the show within the series. Academy Award winner Steven Spielberg, who conceived the show, will executive-produce along with Justin Falvey and Darryl Frank (of DreamWorks), Craig Zadan and Neil Meron ("Chicago," "Hairspray," Promises, Promises; How to Succeed…) and Rebeck, Shaiman and Wittman.

Read Playbill.com's earlier story about the project.