According to the Associated Press, producer Forstater wants a bigger share of proceeds from the musical and is suing members Eric Idle, Michael Palin and Terry Jones as well as former members John Cleese and Terry Gilliam.
A five-day hearing begins Nov. 30 at London's High Court.
Forstater's lawyer, Tom Weisselberg, said that an agreement was made when the film was produced, which stated, "… for financial purposes Mr. Forstater was to be treated as the seventh Python."
Spamalot, which took home the 2005 Tony Award for Best Musical, features a book by Idle, based on the screenplay of "Monty Python and the Holy Grail" by Monty Python creators Graham Chapman, Cleese, Gilliam, Idle, Jones and Palin. The score features music and lyrics by the Grammy Award-winning team of Idle and John Du Prez.