Dunn will assume the role of Sir Bedevere at the Shubert Theatre with Mazzie reprising her work as The Lady of the Lake.
As previously announced, June 24 will feature the arrivals of Stephen Collins as King Arthur and Drew Lachey as Patsy.
Marin Mazzie, recently seen in the New York Philharmonic production of Camelot, is a three-time Tony Award nominee for her performances in Kiss Me, Kate; Ragtime; and Passion. Her other theatrical credits include Into the Woods, Big River, The World Goes 'Round, the City Center Encores! productions of Kismet and Out of this World and Off-Broadway's The Trojan Women: A love Story, where she met husband Jason Danieley. Mazzie also starred in the London production of Kiss Me, Kate, where she earned an Olivier Award nomination for her work, and played a recent stint in the London cast of Spamalot. She was also seen in the Actors' Fund of America's concert staging of On the Twentieth Century.
Wally Dunn has been seen on Broadway in the Bernadette Peters revival of Gypsy as well as One' Mo Time and Master Class and in the national tours of Spamalot, All Shook Up and Master Class. His screen credits include "The School of Rock," "In & Out," "In Dreams," "Herman USA," "The Opportunists," "The Good Shepard," "Law & Order," and "Law & Order: SVU." 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.