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

Matthew Lillard as Shaggy Rogers (voice)

Mindy Cohn as Velma Dinkley (voice)

Grey DeLisle as Daphne Blake (voice)

Danica McKellar as Madelyn Dinkley (voice)

James Patrick Stuart as Whirlen Merlin (voice)

Crystal Scales as Crystal (voice)

Brian Posehn as Marlon Whirlen (voice)

Jeffrey Tambor as Mr. Calvin Curdles (voice)

Diane Delano as Mrs. Alma Rumblebuns (voice)

John DiMaggio as Groundskeeper Amos (voice)

Melique Berger as Upset Mother (voice)

John Stephenson as The Sheriff (voice)

Dee Bradley Baker as Sherman (voice)

Olivia Hack as Treena (voice)

Dave Attell as GPS (voice)