Yuri Lowenthal
Ben Tennyson (voice) (52 eps)
Ashley Johnson
Gwen Tennyson (voice) (52 eps)
Greg Cipes
Kevin Levin (voice) (52 eps)
Dee Bradley Baker
Humungosaur (voice) (52 eps)
John DiMaggio
Aggregor (voice) (30 eps)
Vyvan Pham
Julie Yamamoto / Computer Voice (voice) (11 eps)
Paul Eiding
Max Tennyson / Guard #1 / Guard #2 (voice) (7 eps)
Peter Renaday
Sir George (voice) (6 eps)
Scott Menville
Jimmy Jones (voice) (5 eps)
Juliet Landau
Natalie Tennyson / Melinda (voice) (5 eps)
James Remar
Vilgax (voice) (5 eps)
Alexander Polinsky
Argit (voice) (4 eps)
Kari Wahlgren
Charmcaster (voice) (4 eps)
Fred Tatasciore
Foreman / Surgeon / Hammer (voice) (3 eps)
Rob Paulsen
Baz-El / Forever Knight #1 / Churl #4 (voice) (3 eps)
David McCallum
Professor Paradox (voice) (3 eps)
Dwight Schultz
Dr. Animo / Teacher #2 (voice) (3 eps)
Jeff Bennett
Magister Labrid / Major General (voice) (3 eps)
Wil Wheaton
Mike Morningstar / Darkstar (voice) (3 eps)
Patrick Cavanaugh
Winston / Esoterica / Additional Voices (voice) (3 eps)
Chris Pratt
Cooper (voice) (2 eps)
Greg Ellis
Dagonet / Reporter Chet Rigby (voice) (2 eps)
Peter MacNicol
Oliver / Forever Knight #1 (voice) (2 eps)
Kevin Michael Richardson
Magister Pyke (voice) (2 eps)
Jason Marsden
Antonio (voice) (2 eps)
James Arnold Taylor
Plumber Officer / Brannigan / Kolar (voice) (2 eps)
Molly C. Quinn
Eunice / Computer (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)
Christopher McDonald
Captain Nemesis (voice) (2 eps)
Tara Platt
Jennifer Nocturne (voice) (2 eps)
Zeno Robinson
Alan Albright / Heatblast (voice) (2 eps)
Sean Donnellan
Ben 10,000 / Eon (voice) (2 eps)
Powers Boothe
Sunder (voice) (1 eps)
Peter Stormare
King Xarion / King Viktor (voice) (1 eps)
Beth Littleford
Sandra Tennyson (voice) (1 eps)
J.K. Simmons
Magister Gilhil / Plumber (voice) (1 eps)
Nicholas Guest
Simons / Worker / Guest (voice) (1 eps)
Matt Levin
Cash (voice) (1 eps)
Tara Strong
Serena / Young Ben Tennyson (voice) (1 eps)
Xander Berkeley
Warden Morgg / Trukk (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)
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)
Marianne Muellerleile
Maureen (voice) (1 eps)
Danny Jacobs
Captain / Police Dispatch / Dr. Pervis (voice) (1 eps)
Jim Piddock
King Urien / Color Commentator / Chair Umpire (voice) (1 eps)
Tress MacNeille
Zennith (voice) (1 eps)