Yuri Lowenthal

Ben Tennyson (voice)

Ashley Johnson

Gwen Tennyson (voice)

Greg Cipes

Kevin Levin (voice)

Dee Bradley Baker

Humungosaur (voice)

Jeff Bennett

Major Domo / Hugh (voice)

Chris Pratt

Cooper (voice)

Powers Boothe

Sunder (voice)

Peter Stormare

King Xarion / King Viktor (voice)

Beth Littleford

Sandra Tennyson (voice)

Fred Tatasciore

Foreman / Surgeon / Hammer (voice)

Greg Ellis

Dagonet / Reporter Chet Rigby (voice)

J.K. Simmons

Magister Gilhil / Plumber (voice)

Scott Menville

Jimmy / J.T. / Pilot 2 (voice)

Nicholas Guest

Simons / Worker / Guest (voice)

Peter MacNicol

Oliver / Forever Knight #1 (voice)

Matt Levin

Cash (voice)

Tara Strong

Serena / Young Ben Tennyson (voice)

Kevin Michael Richardson

Kwarrel (voice) · Magister Pyke (voice)

Xander Berkeley

Warden Morgg / Trukk (voice)

Brian George

Victor Valadis / Janitor (voice)

Miguel Ferrer

Magister Hulka / Alpha #4 (voice)

Rob Paulsen

Baz-El / Forever Knight #1 / Churl #4 (voice)

Charlie Schlatter

Tack / Plumber (voice)

Olivia Hack

Emily (voice)

Jason Marsden

Young Max Tennyson (voice)

Paul Eiding

Max Tennyson / Guard #1 / Guard #2 (voice)

David McCallum

Professor Paradox (voice)

Juliet Landau

Natalie Tennyson / Melinda (voice)

James Arnold Taylor

Announcer / Fake Vilgax / Fridge (voice) · Plumber Officer / Brannigan / Kolar (voice)

Adam Wylie

Pierce / Forever Knight #3 (voice)

Dwight Schultz

Sheriff / Dr. Animo (voice)

Molly C. Quinn

Eunice / Computer (voice)

Diedrich Bader

Simian (voice)

Jon Polito

Mizaru (voice)

Alexander Polinsky

Argit (voice)

Tia Texada

Elena Validus (voice)

Keone Young

Julie's Dad / Repair Man / Cop (voice)

Yeni Alvarez

Dr. Borges (voice)

Bill Mumy

Agent Bryson (voice)

Vicki Lewis

Agent Locke (voice)

Peter Renaday

Old George (voice)

Diane Delano

Ma Vreedle / Pretty Boy Vreedle (voice)

Robin Atkin Downes

Sir Cyrus / Additional Voices (voice)

Richard Doyle

Driscoll / Additional Voices (voice)

Khary Payton

Hex (voice)

Kari Wahlgren

Charmcaster (voice)

Christopher McDonald

Captain Nemesis (voice)

Wil Wheaton

Mike Morningstar / Darkstar (voice)

Marianne Muellerleile

Maureen (voice)

Tara Platt

Jennifer Nocturne (voice)

Danny Jacobs

Captain / Police Dispatch / Dr. Pervis (voice)

Patrick Cavanaugh

Winston / Esoterica / Additional Voices (voice)

James Remar

Vilgax (voice)

Jim Piddock

King Urien / Color Commentator / Chair Umpire (voice)

John DiMaggio

Swamps / Rath Albedo / V.O. Announcer (voice)

Vyvan Pham

Erin / Julie Yamamoto (voice)

Zeno Robinson

Alan Albright / Heatblast (voice)

Tress MacNeille

Zennith (voice)

Sean Donnellan

Cameraman / Thug / Tech (voice)