Yuri Lowenthal
Ben Tennyson (voice) (32 eps)
Ashley Johnson
Gwen Tennyson (voice) (32 eps)
Greg Cipes
Kevin Levin (voice) (32 eps)
Dee Bradley Baker
Humungosaur (voice) (32 eps)
John DiMaggio
Vulkanus / Rath (voice) (12 eps)
Vyvan Pham
Julie Yamamoto / Computer Voice (voice) (7 eps)
Peter Renaday
Old George (voice) (6 eps)
Juliet Landau
Verdona Tennyson / Waitress (voice) (5 eps)
James Remar
Vilgax (voice) (5 eps)
Patrick Cavanaugh
Winston / Esoterica / Additional Voices (voice) (3 eps)
Scott Menville
Jimmy Jones (voice) (2 eps)
Rob Paulsen
Baz-El / Forever Knight #1 / Churl #4 (voice) (2 eps)
Jason Marsden
Antonio (voice) (2 eps)
Paul Eiding
Max Tennyson / Guard #1 / Guard #2 (voice) (2 eps)
James Arnold Taylor
Plumber Officer / Brannigan / Kolar (voice) (2 eps)
Molly C. Quinn
Eunice / Computer (voice) (2 eps)
Jeff Bennett
Magister Labrid / Major General (voice) (2 eps)
Alexander Polinsky
Argit (voice) (2 eps)
Dwight Schultz
Dr. Animo / Teacher #2 (voice) (2 eps)
Tia Texada
Elena Validus (voice) (2 eps)
Robin Atkin Downes
Sir Cyrus / Additional Voices (voice) (2 eps)
Richard Doyle
Driscoll / Additional Voices (voice) (2 eps)
Kari Wahlgren
Charmcaster (voice) (2 eps)
Chris Pratt
Cooper (voice) (1 eps)
Powers Boothe
Sunder (voice) (1 eps)
Fred Tatasciore
Staradisimus / Forever Knight #3 (voice) (1 eps)
Greg Ellis
Prince Gyula / Cyborg #2 (voice) (1 eps)
Peter Stormare
King Xarion / King Viktor (voice) (1 eps)
Brian George
Victor Valadis / Janitor (voice) (1 eps)
Miguel Ferrer
Magister Hulka / Alpha #4 (voice) (1 eps)
Charlie Schlatter
Tack / Plumber (voice) (1 eps)
Olivia Hack
Emily (voice) (1 eps)
David McCallum
Professor Paradox (voice) (1 eps)
Adam Wylie
Pierce / Forever Knight #3 (voice) (1 eps)
Diedrich Bader
Simian (voice) (1 eps)
Jon Polito
Mizaru (voice) (1 eps)
Keone Young
Julie's Dad / Repair Man / Cop (voice) (1 eps)
Yeni Alvarez
Dr. Borges (voice) (1 eps)
Bill Mumy
Agent Bryson (voice) (1 eps)
Vicki Lewis
Agent Locke (voice) (1 eps)
Diane Delano
Ma Vreedle / Pretty Boy Vreedle (voice) (1 eps)
Khary Payton
Hex (voice) (1 eps)
Christopher McDonald
Captain Nemesis (voice) (1 eps)
Wil Wheaton
Mike Morningstar / Darkstar (voice) (1 eps)
Marianne Muellerleile
Maureen (voice) (1 eps)
Tara Platt
Jennifer Nocturne (voice) (1 eps)
Danny Jacobs
Captain / Police Dispatch / Dr. Pervis (voice) (1 eps)
Tress MacNeille
Zennith (voice) (1 eps)
Sean Donnellan
Ben 10,000 / Eon (voice) (1 eps)