Principal voice actors •
Yuri Lowenthal Hoodlum, Ultimate Spidermonkey •
Dee Bradley Baker NRG, Astrodactyl, Psyphon, Echo Echo, Wildvine, Caitliff, Hulex Colonel, Thirteen, The Worst, Wildmutt, Stinkfly, Acid Breath, Kraab, Slix Vigma •
Eric Bauza – Diamondhead, Eatle, Upchuck, Chromastone, Driba, Dr. Psychobos, Fistrick, Megawhatt, Articguana, Way Big, Albedo (Galvan form), Bellicus (of Alien X), Pax, Solid Plugg, Ripjaws, Lackno, Mechaneer, Trombipulor, Computrons, Rook Da, Thunderpig, Commander Raff, Cast Iron, Poltroon, Ultimate Albedo, Buzzshock, Ultimate Articguana, Plumber Jerry, Cooper Daniels •
Corey Burton – Malware, Mr. Baumann, Brainstorm, Seebik, Fiskerton, V.V. Argost, Albedo Brainstorm, Kane North/Kangaroo Kommando •
John DiMaggio Zombozo, Bubble Helmet, Four Arms, Rath, Humungousaur, Octagon Vreedle, Vulkanus, Bullfrag, Will Harangue, Ultimate Humungousaur, Tentacle Vendor, Atomix, Whampire, Judge Domstol, Centur Squaar •
David Kaye – Khyber, Cannonbolt, Shocksquatch, Gravattack, Heatblast, Sunder, Frankenstrike, Mallice, Warlord Gar, Ultimate Gravattack, Thumbskull, Forever King Joseph Chadwick (second appearance), Lord Transyl, Deefus Veeblepister, Unitaur, Slapstrike, Exo-Skull, Skurd •
Rob Paulsen – Magister Patelliday, Rhomboid Vreedle, Ditto, Captain Kork, Tummy Head, Gorvan, Phil Billings, Gutrot •
Kevin Michael Richardson – Snare-Oh, Blitzwolfer, Emperor Milleous, Cookmeister, Sir Morton, Plumber Dispatcher •
Tara Strong – Ben Tennyson (5, 10, and 11-years-old), Pakmar, Mazuma, Natalie Alvarez, Ben Tennyson of Dimension 23, Y-It, Molly Gunther, Brown Bag, Princess Attea, Lucy Mann, Pesky Dust (later appearances), Albedo (11-year-old Ben form), ML-E (first appearance), ML-E's Mother, Duffy, Swift, Diamondhead Gwen
Additional voices •
Charlie Adler – Professor Blarney T. Hokestar, Cow Alien, Chicken Alien, Collectimus, Proctor Servantis •
Carlos Alazraqui – Rad Dudesman, Scout, Pyxi •
Aziz Ansari – Billy Billions •
René Auberjonois – Azmuth, Azmuth of Dimension 23, Intellectuary •
Diedrich Bader – Simian •
Ogie Banks – Zak Saturday •
Jeff Bennett – Kundo •
Steven Jay Blum – Vilgax, Hobble, Zs'Skayr, Ghostfreak, Professor Helena Xagliv, Bill Gacks, Adwaita, Pa Vreedle, Thaddeus J. Collins •
Kimberly Brooks – Princess Looma, Serena (of Alien X), Madison, Rayona, Rook Bralla •
Bettina Bush – Kai Green •
Greg Cipes –
Kevin Levin •
Jeffrey Combs – Kuphulu •
Jim Cummings – Vexx, Hulex Colonel •
Tim Curry – Forever King Joseph Chadwick (first appearance) •
Diane Delano – Ma Vreedle •
Michael Dorn – Dr. Viktor •
Dave Fennoy – Tetrax Shard of Dimension 23 • Michael Goldstrom – Benevelon •
Jennifer Hale – Rojo, Suemongousaur •
Mark Hamill – Maltruant •
Jon Heder – Clyde Fife •
Ashley Johnson –
Gwen Tennyson, Margie, Wildvine Gwen, Cannonbolt Gwen, XLR8 Gwen •
Tom Kenny – Bezel •
Phil LaMarr – Jonesy •
Juliet Landau – Helen Wheels, Magistrata •
Beth Littleford – Sandra Tennyson, Isosceles Right Triangle Vreedle •
Morgan Lofting – Fistina, Yetta •
Vanessa Marshall – Drew Saturday •
David McCallum – Paradox •
Edie McClurg – Vera Tennyson •
Christopher McDonald – Carl Nesmith/Captain Nemesis •
Scott Menville – Jimmy Jones, Chrono Spanner/Kenny Tennyson •
Kate Micucci – Luhley • Miguel Nájera – Wes Green •
Judd Nelson – Ben 10,000, Eon •
Khary Payton – Manny Armstrong, Hex •
Vyvan Pham – Julie Yamamoto, Ship •
Charles Phoenix – Charles Zenith •
Tara Platt – Ester, ML-E (second appearance), J-NE, Subdora, Jennifer Nocturne •
Alexander Polinsky – Argit •
Kevin Schon – OTTO •
Dwight Schultz – Dr. Animo •
Cree Summer – Frightwig •
Tia Texada – Elena Validis •
Alanna Ubach – Rook Shar, Rook Ben •
Kari Wahlgren – Charmcaster, Viktoria •
Wil Wheaton – Darkstar, Dante •
April Winchell – Queen Voratia Rumbletum •
Gwendoline Yeo – Nyancy Chan, Sheelane ==Crew==