Tony Cervone Director Will Forte Shaggy Rogers Voice Mark Wahlberg Blue Falcon Voice Jason Isaacs Dick Dastardly Voice Gina Rodriguez Velma Dinkley Voice Zac Efron Fred Jones Voice Amanda Seyfried Daphne Blake Voice Kiersey Clemons Dee Dee Skyes Voice Ken Jeong Dynomutt Voice Tracy Morgan Captain Caveman Voice Frank Welker Scooby-Doo, Pterodactyl Voice Iain Armitage Young Shaggy Voice Mckenna Grace Young Daphne Voice Pierce Gagnon Young Fred Voice Ariana Greenblatt Young Velma Voice Simon Cowell Himself Voice Christina Hendricks Officer Jaffe Voice Henry Winkler Keith Voice Harry Perry Himself Voice Adam Sztykiel Screenwriter, Executive Producer Jack Donaldson Screenwriter Derek Elliott Screenwriter Matt Lieberman Screenwriter Pam Coats Producer Allison Abbate Producer Charles Roven Executive Producer Richard Suckle Executive Producer Jesse Ehrman Executive Producer Dan Povenmire Executive Producer Chris Columbus Executive Producer Ryan Folsey Film Editing Vanara Taing Film Editing Junkie XL Original Music Michael Kurinsky Production Design Emil Mitev Art Director Ruth Lambert Casting