Frank Welker as Scooby-Doo / Fred Jones / Self

Matthew Lillard as Norville 'Shaggy' Rogers / Self - Voice of "Shaggy"

Grey DeLisle as Daphne Blake / Self - Voice of "Daphne"

Kate Micucci as Velma Dinkley / Self - Voice of "Velma"

Janel Parrish as Janel Parrish - Host

Jerry Beck as Self - Animation Historian and Author

David Silverman as Self - Director and Producer, "The Simpsons"

Seth Green as Self - Actor, "Scooby-Doo 2: Monsters Unleashed"

Tony Cervone as Self - Director, "Scoob!" / Showrunner, "Mystery Incorporated"

Tom Sito as Self - Animator, Historian

Joseph Barbera as Self - Hanna-Barbera Co-Founder (archive footage)

Mary Lynn Rajskub as Producer Bryn

Baron Vaughn as Bram Penobscot - Scooby's Vocal Coach

Casey Kasem as Shaggy Rogers (voice) (archive footage)

Diedrich Bader as Batman - Concerned Citizen (voice)

'Weird Al' Yankovic as Self - Singer, Songwriter, Accordionist

Olivia Liang as Olivia Liang - Shaggy's Martial Arts Trainer

Karamo Brown as Costume Designer Carter

Mitch Watson as Self - Showrunner, "Mystery Incorporated"

Cheri Oteri as Lazlo the Mechanic

Brendan Jennings as Arlo Davidsonman - Team Scooby

Vadym Krasnenko as Snow Ghost

Lindsey Alena as Additional Voices (voice)

Dominic Catrambone as Additional Voices (voice)

Fred Tatasciore as Additional Voices (voice)