The show's voice director is Lisa Schaffer.
Main Callisto family • Miles Callisto (voiced by Cullen McCarthy in season 1 and Justin Felbinger in seasons 2 and 3) is an enthusiastic and curious 10-year-old boy with a somewhat reckless inventive streak. He is also the captain of the newly established Mission Force One. He possesses a hovering
skateboard called a "blastboard" and a
boomerang known as a "lazerang". As the captain of Mission Force One, he uses a blast shield that doubles as a blastboard, as well as a lazerang that can extend and become a staff. • Loretta Callisto (voiced by Fiona Bishop) is Miles' big sister who is 11 years old and the brainier of the two children. She is a technology whiz. She also likes to read directions and follow the rules. • Admiral Crick (voiced by
Diedrich Bader) – One head of the Tomorrowland Transit Authority, who is seen to be more comedic (intentionally or not) of the siblings. Watson and Crick are named after
James Watson and
Francis Crick, who discovered the structure of DNA.
Recurring • Joe Callisto (voiced by
Adrian Grenier) is an intergalactic crime fighter, Leo's brother, and Miles and Loretta's uncle. He is accompanied by the robotic dog Cap9. • Vincent Callisto (voiced by
Jonathan Frakes) is Leo's father and retired captain of the TTA ship
Explorer • Gadfly Garnett (voiced by
Mark Hamill) is an alien outlaw obsessed with owning the latest technology. • Spectryx (voiced by
George Takei) is an alien from the planet Parallax who can only see in infrared. • Professor Randii Rubicon (voiced by
Bill Nye) is a scientist who mostly studies Neptune and the Builders. He gave the Cosmic Explorers and Loretta a tour of the Trident Research Station in Neptune. • Axel is a robot that the admirals sent to the Callistos as a replacement for M.E.R.C. He is strong and helpful, but also very uncaring. Because of this, he was recalled by the admirals, who allowed M.E.R.C. to stay with the Callistos. • Commander S'leet (voiced by
Wil Wheaton) who's a secondary villain until the third season, who can seemingly disappear, as if digitally. • Lysander Floovox (voiced by
Alton Brown) • Auntie Frida (voiced by
Brenda Song) is Phoebe's sister. She can do a one-arm
handstand on Mars and paints while doing so. • Mr. Avon Xylon (voiced by
Dee Bradley Baker) is an alien mailman. Baker also voices Lieutenant Luminex, Captain Joe's second-in-command. • The Game Master (voiced by
Whoopi Goldberg) is a play creative tech genius. • Dr. Consilium (voiced by
LeVar Burton) is a Galactic School teacher. • Dr. Zephyr Skye (a.k.a. Dr. Z.; voiced by
Ginger Zee) is Tomorrowland's leading meteorologist. • Haruna Kitumba (voiced by
Issac Ryan Brown) is Miles's best friend and neighbor prior to Miles' departure to space who serves as a navigator of the Mission Force One. His Mission Force One armored suit gives him the ability to punch through anything. • Pipp Wimpley (voiced by
Ethan Wacker) is a young alien from the oceanic planet Atlantix. • Mirandos (voiced by Ivy Bishop) is a young intelligent Ariellian from the planet Tempestoro who serves as an engineer of Mission Force One. She wears gloves known as "Solidizer gloves" that can create any object. • Dashiell Scamp (voiced by
Diedrich Bader) is an alien who "trades" for robots and leaves
newton balls in exchange. • Zeno (voiced by
Manny Montana) is the computer voice of the starship
Zenith. • Commander Nemex (voiced by Elan Garfias) is the cruel commander of the Nemesystems. He is later revealed to be Silas, a TTA Cadet who was rejected from Mission Force One due to his dislike of working with others. • Aggro (voiced by
John DiMaggio) is the second-in-command of the Nemesystems.
Blopp family • Captain Bobble Blopp (voiced by
Danny Jacobs) • Blippy Blopp (voiced by
Tom Kenny) • Blodger Blopp (voiced by
Sam Lavagnino) is the son of Bobble and Blippy, Miles' friend from planet Bloppsburgh who serves as a ship operator of Mission Force One. He is able to transform into any inanimate object.
Dethalians • Queen Gemma (voiced by
Grey Griffin) is the queen of the Dethalians. Ever since Gadfly tried to steal her technology, she does not trust anyone who trespasses into her territory uninvited. However, in some episodes, she becomes a reluctant ally and shows a kinder side. She loves her son Rygan and is very protective of him. • Prince Rygan (voiced by Rio Mangini) is Queen Gemma's son. Rygan made friends with Miles and helped him and his family escape after Queen Gemma arrested them for entering her kingdom without permission. In
Scavengers of Mars, he becomes a Cosmic Explorer and joins the scavenger hunt. ==Production==