Both artists are scheduled to play a six-month engagement. Butler, who will perform six shows a week, succeeds Savannah Wise in the role of Sherrie; Lenk succeeds Wesley Taylor as Franz. Wise and Taylor played their final performances Sept. 13. (Ericka Hunter and Jeremy Jordan took on the roles in the interim period.)

Rock of Ages currently stars Constantine Maroulis, James Carpinello, Adam Dannheisser, Mitchell Jarvis, Michele Mais, Lauren Molina, Don Stephenson, Bahiyah Sayyed Gaines, Ericka Hunter, Jeremy Jordan, Michael Minarik, Angel Reed, Eric Sciotto, Becca Tobin, Katherine Tokarz, Andre Ward, Tad Wilson and Jeremy Woodard.

Lenk portrayed Andrew on TV's "Buffy the Vampire Slayer." Rock of Ages will mark his Broadway debut.

Prior to Xanadu, Kerry Butler was most recently on Broadway as Audrey in Little Shop of Horrors. She portrayed Penny Pingleton in the original Broadway cast of Hairspray, and her other Broadway credits include Belle in Beauty and the Beast, Eponine in Les Misérables and Ms. Jones in Blood Brothers. Off-Broadway she was seen in Bat Boy The Musical, The "I" Word, Prodigal and The Folsom Head. She was also part of the cast of the musical The Opposite of Sex, which premiered in San Francisco. She was most recently seen in the Seattle premiere of Catch Me If You Can.

Rock of Ages premiered on Broadway March 17 and officially opened April 7 at the Brooks Atkinson Theatre. Kristin Hanggi directs the Tony-nominated production that was penned by Chris D'Arienzo and features choreography by Kelly Devine and music supervision, arrangements and orchestrations by Ethan Popp. "In 1987 on the Sunset Strip," Rock of Ages production notes state, "a small town girl met a big city rocker and in L.A.'s most famous rock club, they fell in love to the greatest songs of the '80s. . . . [The musical is] an arena-rock love story told through the mind-blowing, face-melting hits of Journey, Bon Jovi, Styx, Reo Speedwagon, Pat Benatar, Foreigner, Twisted Sister, Poison, Asia, Whitesnake and many more."

The Brooks Atkinson Theatre is located in Manhattan at 256 West 47th Street. For tickets call (212) 307-4100 or visit www.ticketmaster.com.