Petkoff will step into the roles of Sir Robin, Guard 1 and Brother Maynard, according to a show spokesperson. He succeeds former "American Idol" contestant Clay Aiken, who played his final performance May 4.

Petkoff joins a cast that currently includes Tom Deckman, David Hibbard, Jonathan Hadary, Rick Holmes, Bradley Dean, Steve Rosen, Hannah Waddingham, Kevin Covert and Matthew Crowle.

Robert Petkoff has been seen on Broadway in Fiddler on the Roof and Epic Proportions and Off-Broadway in More Stately Mansions. He appeared in The Royal Family in the West End, on tour with Spamalot and in productions of Tantalus, The Importance of Being Earnest, Sunday in the Park With George, Hamlet and Romeo and Juliet. Petkoff's screen credits include "Milk & Money," "Loverboy," "Game Day," "Chappelle's Show," "Law & Order," "Hack," "Quantum Leap," "Married With Children" and "Mona."

Spamalot features a book and lyrics by Eric Idle, music by John Du Prez and Eric Idle, direction by Mike Nichols, choreography by Casey Nicholaw and is based on the screenplay of "Monty Python and the Holy Grail" by Monty Python creators Graham Chapman, John Cleese, Terry Gilliam, Eric Idle, Terry Jones and Michael Palin.

The musical tells the tale of King Arthur and his Knights of the Round Table on their quest from God for the Holy Grail — with a short stop in the dazzling Spam-filled land of Camelot.

Spamalot earned the 2005 Tony Award for Best Musical and took home honors for direction (Mike Nichols) and one of its stars (Sara Ramirez).

Spamalot celebrated its third anniversary on Broadway March 18. On Broadway Spamalot plays Tuesday-Friday at 8 PM, Saturday at 2 and 8 PM and Sunday at 2 and 7 PM.

For more information visit www.montypythonsspamalot.com.