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• Natasha Lyonne as Gaz Digzy, a star athlete in "The Game" and a former captain of the Boom Boom Boys, who wrecked her own career due to sheer boredom and subsequently found herself teamless, out of shape, and maligned by various diseases. She is foul-mouthed, hard drinking has-been whose only hope is to join the Leptons and reclaim her glory. Though Ace Ambling, the young lead player of the Leptons, looks up to her, she usually ridicules him, but she slowly begins to appreciate his appraisal of her. Despite constantly being drunk, she is shown to be very knowledgeable in playing the Game and occasionally shows competence and teamwork skills. By the end of Season 1, she warms up to the Leptons and decides to stay as their new captain. In Season 2, Gaz's full name is revealed to be Gazmerelda Digzfield, daughter of moon mining tycoon Rupert T. Digzfield IV, and it is also revealed that she became a player in the Game as a way of getting back at her uptight biological family. As the series progress, she became more sociable, happy, and responsible due to spending time with the Leptons, particularly Ace who brings the best out of her due to his unwavering faith and belief in her. Near the Season 2 finale, she began to get back in shape and decided to train sober and become clean. To show her growth as a person, she became selfless and was willing to give up her family fame and fortune by disowning her father to go back leading the Leptons once more, and stated that her true family are the Leptons, who truly loved her and accepted her for who she is and had given her the sense of belonging she never got in her whole life.
• Jessica DiCicco as Ace Ambling, a 12-year-old orphan and the lead player of the Leptons. He is bright, cheerful, and optimistic, but can lose his patience when things don't go as planned. He looks up to Gaz, and though he seems oblivious to her indifference to him, he eventually realizes her flaws and attempts to bring out the best in her. Despite his cheery demeanor, he often feels neglected or looked down upon by the team. Ace is revealed to be descended from the Ballmasters who fought in the Rad Wars; he can become one by fusing with Babyball and can change forms while doing so.
  • DiCicco also plays Duleena "Dee Dee" Duneeda, an anime-esque girl on the team. She is a mood swinger, alternating between being soft-spoken and caring and enraged and violent, usually when provoked. She is also shown to have a crush on Leto and gets angered when he tries to downplay his relation to her. She is a former vampire hunter and thus has a large amount of knowledge on the occult.
• Dana Snyder as Babyball, a crass and cynical The Game ball who is similar to Gaz Digzy, he looks down on his own team and wishes for better players. However, he can access a special ability when paired with Ace, whom he dislikes due to his cheeriness; he does begin to warm up to Ace and eventually calls him his friend. Despite this, Babyball is selfish, boastful, and will mock his teammates regardless.
  • Snyder also voices Stinkfinger, a living severed finger that reeks and is part of the rival team, the Murderous Misfits.
• Eric Bauza as Flypp Champion, a body stump with a spiked "sensory deprivation" helmet. A true warrior, Flypp must rely on his navel to perform certain tasks. Despite claiming to have amazing abilities, which he arguably does, he still seems rather useless and is typically brushed aside with ease by other players. He was apparently once a great defender of the innocent, but through a series of training regimes, chose to simplify himself and put all his energy in his power Umbilicus, a large umbilical cord that extends from his navel. Flypp is boisterous, but also egotistical, fancying himself a mighty warrior despite his frequent failures. While his name is officially spelled "Flypp", some of the promotional and in-show material spells it as "Flipp".
• Dave Willis as Leto Otel, a lethargic and pessimistic member of the Leptons. He lacks the motivation and prowess to be an effective player and does not seem interested in the Game, to the point that he is not phased by mortal injuries. He quotes poetry and seems intelligent at times. While Dee Dee openly shows affection for him, Leto is reluctant to reciprocate. He has at times revealed to become sad, more so than usual, when Dee Dee briefly leaves.
• Christy Karacas as Crayzar, the ruler of the Consortium who created the Game to please humanity. He has lived for thousands of years and lacks any sort of genitalia, as he is implied to be some type of artificial lifeform. He lived through the Rad Wars and gave life to all of the game balls, which were originally used as weapons in the wars. He seemingly admires the Leptons, but after Ace and Babyball's fusion, might have ulterior motives. In the Rubicon special, its revealed that Crayzar is of a demigod species known as the Saytars, with his true name being Gold Saytar, and that he went against his assigned mission to find the "Cosmo Diary" by tricking all of Earth into worshipping him as a god via The Game.
  • Karacas also plays Aboo Buvu, a The Game ball with sunglasses who reports the news and acts as a moderator for The Game. In some material produced for the show, he is referred to as Blabberball.
• Christopher McCulloch as various characters.

The Leptons also include two characters who do not have voice actors but are prominent: Lulu, a large green ape-like creature with a cowardly personality; and Bob, a diminutive grey alien, who appears to be useless and typically gets beaten the worst.

Guest

• Norman Reedus as Bacchus LaBrute, the blue-skinned alien Greaser-style leader of a notorious biker gang called the Middle Fingers who live out in the wastelands.
• Stephanie Sheh as Luna, the leader of the Sailor Moon-esque team the Ashigari Princesses and an old rival of Gaz who wants to steal the secret of the Ballmaster formation.
  • Sheh also plays Rudy Drax, a child without limbs, who idolizes Flypp Champion.
• Mike O’Gorman as Buddy Marinara, the Leptons' two-faced manager who is always looking for a way to exploit his team's newfound fame.
  • O'Gorman also plays as a shopkeeper of an Animal Shelter that Ace volunteers at.
• Jo Firestone as Ace's Robot Mother, a fake robot mother that Gaz and Babyball make to cheer him up.
• Rachel Dratch as The Blab, a talking STD parasite that grows out of Gaz's stomach.
• Cree Summer as Obah Wexley, a famous talk show host. She is a parody of Oprah Winfrey.
• Doc Hammer as Milky van Montebag, a manager who tries to cash in on Ace's fame.
  • Hammer also plays as the mecha butler in Rupert's mansion.
• Ed Asner^[9] as Rupert T. Digzfield IV, Gaz's evil mega-rich father and founder of the Digzfield Lunar Drilling Corporation.
• Joshua Henry^[10] as Demon Saytar, Crayzar's father.
• Timothy Levitch as Tyetaynus, Crayzar's younger brother.

Season 1 (2018)

Phil Ahn and Christy Karacas provide the storyboards for every episode, but there are different co-storyboarders that work with them depending on the episode.

Season 2 (2020)

Ballmastrz: Rubicon (2023)

Development

Around 2014, Karacas began working on the show.^[20] On May 7, 2015, it was announced that Adult Swim had given a pilot order to the production as part of their 2015-16 slate of returning series, pilots and specials.^[21] The pilot would become Ballmastrz: 9009. On August 4, 2017, it was announced that Adult Swim had given the production a series order consisting of the first season. The series was created by Christy Karacas, co-creator of Superjail! and produced by animation company Titmouse, Inc.^[8]

Animation

The series is animated with Adobe Animate and produced by a team of around 20 animators from Titmouse, Inc. offices in New York City. When the animators were discussing the artistic direction of the series, Titmouse president and producer Chris Prynoski described the show's animation style as appearing "like it was drawn by High School kids who try to draw anime".

For the Ballmastrz: Rubicon special, the animation team was changed to Studio 4°C. Karacas stated that the decision was done as he wanted the special to "dive into the actual anime world."^[6] As a result, the special features a new art style.

Casting

Alongside the initial series announcement, it was reported that Natasha Lyonne was cast in the series' lead role of Gaz Digzy. The main cast was also set to be rounded out by Dana Snyder, Dave Willis, Jessica DiCicco, Eric Bauza, Christopher McCulloch, and Karacas. Guests were set to include Norman Reedus, Stephanie Sheh, and Mike O’Gorman.^{[8][22][23][24]}