Kid Cosmic

• Jack Fisher as Kid,[2] an excitable nine-year-old child who finds the Stones of Power and uses them to fulfill his dream of leading his own superhero team. His real name is never revealed, and is just referred to as "Kid" or "The Kid" by the other characters. His hero name is Kid Cosmic and he wears the green Stone of Power, which grants him telekinetic powers he uses through most of the first season for flight. In the second season he uses the light green Goo Stone that allows him to take a gelatin like form that he and his partners find disgusting. He lost his parents to a car collision with a semi-truck one night, and now lives in a junkyard owned by his grandpa, Papa G.[7] Kid also shows to have some minor PTSD, from that fatal night that he lost his parents. Being a poor kid, he collects all sorts of old stuff his grandpa has recollected, including video games, comics and records.[7]
• Amanda C. Miller as Johanna "Jo",[2] a waitress at her mom's diner who dreams of seeing the world, and is granted the power of portal creation by the purple Stone of Power. Her hero name is Portal Girl and also leader of the team.
• Lily Rose Silver as Rosa Flores,[2] a Mexican four-year-old girl who is granted the power to enlarge herself to gigantic proportions by the blue Stone of Power. Her hero name is La Niña Gigantica, which is Spanish for "The Gigantic Girl". She is the daughter of Ramona and Carlos Flores.
• Tom Kenny as Stuck Chuck,[2] an alien who is among the first to try and steal the Stones of Power from Kid, and who ends up stuck with Kid's group when, as a result, he loses both his ship and legs. His name is a nickname thought up by Jo, with his real name never revealed, and he also was the one who caused the spaceship with the stones to crash on Earth. Initially seeking any opportunity to get the stones for his Great Leader, he reforms near the end of the first season. In season two, he works as a dishwasher in Mo's Oasis and gains the dark blue Stone of Power of pain absorption.
• Fred Tatasciore as Tuna Sandwich,[2] a cat who resides at Mo's Oasis and to whom Kid gives the red Stone of Power, granting him the power to see glimpses of the future. His hero name is The Precognitive Cat. Tuna wears a high-tech collar that translates his speech into English, given to him by Chuck as of "The Invaders from Earth."
• Keith Ferguson as:
  • George "Papa G",[2] Kid's hippie maternal[9] grandfather who encourages Kid to find nonviolent solutions to his problems, and who is granted the power to clone himself by the yellow Stone of Power. His hero name is Old Man Many Men. His design and his personality are very similar to Wander from McCracken's third animated series, Wander Over Yonder.
  • Carl, a trucker and regular at Mo's Oasis. In the second season, he gains the ability to turn invisible through the turquoise Stone of Power.
• Kim Yarbrough as Flo,[10] Jo's mother and proprietor of Mo's Oasis. She tries to keep her business floating even when she has to deal with Kid Cosmic antics, including having her diner in space. Despite that, she decides to support Jo even if she prefers to get mentorship from Queen Xhan. She tends to use several of the Power Stones Jo finds in the second season while she never dominates the use of one.

• Christian Lanz as Carlos Flores,[10] Rosa's father and a regular at Mo's Oasis and Romona's husband. He and his wife run a successful floral business. In the second season, he gains the white Cosmic Stone of Power, which grants the user the ability to breathe ice.
• Grey Griffin as:
  • Carla, a biker and regular at Mo's Oasis. She becomes part of the Local Heroes by getting the pink Cosmic Stone of Power that allows her to run at super speed.
  • Ramona Flores, Rosa's mother and a regular at Mo's Oasis and the wife of Carlos. In the second season, she gains the orange Cosmic Stone of Power, which grants the user the ability to breathe fire.[10]
• Rich Fulcher as Zarkon,[10] a small green alien and an adversary of Kid and his friends. Despite being easily able to defeat the Local Heroes and take the stones, he ends up getting electrocuted to death when he flies into a power line.
• Jason Hightower as Biker in Black,[10] the leader of Earth Force Enforcement Force who believes all aliens who come to Earth are hostile.
  • Earth Force Enforcement Force consists of Lanz as Crimson Vision, Griffin as Violet Vanish, Eric Bauza as Emerald Wing, Phil LaMarr as Golden Swarm, and Michaela Dietz as Blue Behemoth.[10] Their colors correspond to the powers granted by the Stones of Power. They follow Biker in Black's orders to dispose of all aliens on Earth, but when their suits are destroyed at the end of the first season, they reform themselves.
• Cree Summer as Queen Xhan,[10] a purple jellyfish-like alien who is the former bearer of the purple Stone of Power. She ends up being the only survivor of her group of friends at the end because of Erodius the Planet Killer. She acts as Jo's mentor in terms of leadership in the second season, and during it, she loses one of her tentacles when Fantos tears it off to use as a weapon and is forced to escape with the other aliens from Mo's Oasis Cafe when the cafe itself is being destroyed by Erodius. Is revealed that she was not able to pull her comrades out of Erodius gravity on time having to run away to Earth creating a portal.
• Fred Tatasciore as:
  • Great Leader, the evil, cowardly ruler of Stuck Chuck's people.
  • Gortho the Gargarian, a yellow goblin-like creature who was the former bearer of the yellow Stone of Power. He died by being pulled by Erodius gravity in a fateful battle where only Queen Xhan survives.
  • Meep, a small light blue insect-like alien who was the former bearer of the blue Stone of Power. He died by being pulled by Erodius gravity in a fateful battle where only Queen Xhan survives.
  • Hamburg, a guy who works at Mo's Oasis Cafe and is usually seen with Fry. He obtains the dark purple multiple arms Cosmic Stone of Power in the second season.
• Eric Bauza as:
  • Mstr Wlkzn, a green humanoid alien with an enormous head and swirly eyes who was the former bearer of the green Stone of Power. He died by being pulled by Erodius gravity in a fateful battle where only Queen Xhan survives.
  • Fry, a man who works at Mo's Oasis Cafe and is usually seen together with Hamburg. He obtains the light pink elasticity Cosmic Stone of Power in the second season, which gives the user the ability to stretch their body.
• Sam Riegel as PT-SB, a black and red robot who was the former bearer of the red Stone of Power. He died by being pulled by Erodius' gravity in a fateful battle where only Queen Xhan survives.
• Bobby Moynihan as Fantos the Amassor, an evil, immature fanboy of Erodius the Planet Killer, who is obsessed with obtaining all 13 Cosmic Stones of Power in order to help Erodius destroy the universe. He also lives with his mother and goes to her for emotional support. His design, along with his motives, are a reference to Thanos, with his battle armor being a more blatant reference to Galactus.[11]
• Erodius the Planet Killer, a mysterious, sentient rogue planet that generates a powerful gravity well to destroy other planets and absorb them into its body as it travels in a single direction throughout the cosmos. it is possibly a reference to both Ego the Living Planet and Mogo. At the end of the second season, it is defeated when the Local Heroes use the Goo and Growth Stones to cause it to explode from the inside.
• April Winchell as Krosh, an alien warrior who was the previous champion of the Fight Hole. She allies temporally with Jo to beat Erodius but she was killed by Fantos, after trying to steal the Power Stones, when he vaporizes her and her duplicates into nothing but ash.
• Toks Olagundoye as Madame President, the leader of a tiny civilization whose planet was destroyed by Erodius and uses a room of Mo's Oasis motel to rebuild their civilization. At the end they run away with Queen Xhan when Mo's House is destroyed.
• Nicolas Cantu as Ensign Mainstay, the second on board of the tiny civilization that is cautious about the intentions of Flo until he realizes the big effort the Local Heroes did to save them.
• Cathy Cavadini, Tara Strong and E. G. Daily as (respectively) Agent Pink, Agent Blue, and Agent Green of the PPG (Planet Protection Group), a new government agency who first appear at the end of the second season after the destruction of Erodius the Planet Killer. Their codenames, hairstyles, and actresses all reference the eponymous characters of McCracken's first animated series, The Powerpuff Girls.

• Mo, Flo's mother and Jo's grandmother who was the founder of Mo's Oasis Cafe. She died before the events of the series.
• Kid's unnamed, deceased mother and father who were killed in a car collision with a semi-truck before the events of the series. Their deaths were so horrible that Kid was traumatized after that incident and said lethal accident was what caused Kid to dream of being a superhero.
• Grey Griffin as Boss Fiosa, an evil alien crime boss who possessed the fire and ice Stones of Power before the Local Heroes pulled off a heist to take them from her.
• Fantos' mother, an elderly alien woman who is the mother of Fantos who he lives with and goes to for emotional support. In the end of the second season, she disowns her son and dumps his belongings on Erodius.
• Crushtaceor
• Corgor the Conqueror
• Lord Koregore
• Carlax
• Saucerman
• Death Dogs
• Grathla

The main setting of the show, an arid landscape with a "generic rural southwest desert vibe", is presumed to be New Mexico. However, McCracken said in an interview for Den of Geek: "It could be New Mexico, it could be California [or] it could be Arizona. Basically it’s a remote enough place where a spaceship could crash and not a lot of people would know about it."[21]

Stylistically, the show is meant to resemble the visual look of classic comics such as Hank Ketcham's Dennis the Menace and Hergé's The Adventures of Tintin,[2][3] where every action is grounded in reality: "A lot of the choices that we made in Kid were based on the fact that these are real people in the real world [...] So with the animation we avoided overly smooth and flowy actions or lots of squash and stretch, things that you associate with cartoons," the creator said.[21] Stuck Chuck's design is a nod to the aliens from the 1996 film Mars Attacks! and other science-fiction movies.[22] Sometimes spaceships, cars, and major locations, like Mo's Oasis Café, are represented by 3D models.[23]

McCracken affirmed that some of the ideas explored within the show are also based on things that he personally experienced, such as the loss of his father at the age of 7, similar to the protagonist, who lost both of his parents.[16] The dynamics between Kid and Jo are loosely based on McCracken's relationship with his older sister and are similar to those of Mac and Frankie in Foster's Home for Imaginary Friends.[22] Rosa's "playful spirit" is also a reflection of the creator's young daughter.[3][8]

Kid Cosmic also plays on the theme that "heroes help, not hurt", which means the characters often show a compassionate attitude toward their adversaries.[16] This strays in tone from McCracken's first popular work, The Powerpuff Girls, which he described as a "campy parody of superheroes".[16] He declared: "I really didn't want to tell a story to kids that said, 'Hey, if you get great powers, then you can go and beat up bad guys and be violent and win.' I didn't want that to be the message. So I asked myself what a real hero is".[16]

In late February 2021, Netflix released a soundtrack album titled Kid Cosmic and the Sonic Courage. Under the name of the show's fictional "70's psychedelic garage punk band" Dr. Fang and the Gang, the soundtrack features music and songs of the first season written, composed and performed by multi-instrumentalist Andy Bean. He had previously written and composed the soundtrack for McCracken's Wander Over Yonder.[24]