Matthew Lillard as Shaggy Rogers (voice)

Frank Welker as Scooby-Doo / Fred Jones / Monster (voice)

Grey DeLisle as Daphne Blake (voice)

Kate Micucci as Velma Dinkley / Sandi (voice)

Jason Isaacs as King Arthur Pendragon (voice)

Nick Frost as Merlin (voice)

Greg Ellis as Herald / Herman Ellinger / British Passenger (voice)

Spike Brandt as Mr. HB (voice)

Ted Barton as Mayor Saunders / Sir Lancelot (voice)

Stephen Stanton as Peanut Vendor (voice)

Kari Wahlgren as Female Peasent (voice)

Fred Tatasciore as Black Knight (voice)

Trevor Devall as Man Cat (voice)