Mighty Atom (Tetsuwan Atomu; "Astro Boy") - The robot boy fashioned after Tobio Tenma (TENMA Tobio; "Toby Boyton" aka Astor Boyten III), he possesses the strength of 100,000 horsepower (later 1,000,000) and the heart of gold. He has seven amazing powers: flight, multiple languages, analytical skills, headlight eyes, strength, hidden weapons in his back and the ability to tell what's right and wrong. In addition he has a built-in geiger counter and radio system plus hypersensitive hearing. He first appeared in Episode 1: Birth of Astro Boy.

Uran (Uran)/Zoran - Astro's cybernetic sister; a superhuman android with a naive, tomboyish personality. Constructed by Dr Elephun as a "gift" for Astro, Uran is an extremely mischievous little girl who constantly lands her older brother in trouble. While lacking Astro's weaponry and propulsion systems, she in extremely powerful (50,000 horsepower) and regularly accompanies him on various missions (or attempts to). Like Astro, she is fully capable of experiencing human emotions - though being somewhat less 'mature,' she sometimes expresses them by being naughty or disobedient. Uran first appeared in Episode 25 (The Strange Birthday Present) under the name Astrogirl; in the manga she has always been known as Uran (although in the 2000 anime series she was renamed Zoran). In the 2003 anime & Naoki Urasawa's Pluto Uran has the ability to communicate with animals.

Dr. Umatarō Tenma (TENMA-hakase; "Dr. Aster Boyton II") - The former head of the Institute of Science. Ever since his son passed away, he decided to build a robot boy who looks like his son. But when he discovered that Astro Boy couldn't grow, he sold his son to the circus. He only appears in Episodes 1: Birth of Astro Boy, and 97: Mystery of The Metal Men.

Hoshie Tenma (TENMA Hoshie) - deceased wife of Dr. Umatarō Tenma and mother of Tobio Tenma. Her facial features are taken from Michi, a superhuman being created from synthetic cells in the manga version of Metropolis. This is quite appropriiate as Michi was something of a spiritual predecessor to Astro and in a way could even be seen as his mother. Hoshie was the model for Atom's robotic mother as seen in volumes seven and Eight of the Astroboy Manga. See Tezuka in English's Hoshie Tenma page for more details. [1]

Professor Ochanomizu (OCHANOMIZU-hakase; "Dr. Packerdermus J. Elefun") - The present head of the Institute of Science and a fearless campaigner for robotic rights. Kind, patient and good-natured, he serves as a mentor for both Astro and Uran, and would willingly give his life for either. Somewhat eccentric by nature, he tends to be excitable when faced by a scientific mystery, particularly when his opinions are questioned by his scientific colleagues. He first appeared in Episode 1: Birth of Astro Boy, where he rescued Astro from Caccitore's circus.

Police Inspector Tawashi (Tawashi-keibu; "Inspector Gumshoe") - a highly-placed police detective with an innate distrust of androids and robots. Due to his opposition to Tokyo's robotic population, Gumshoe has a long-standing feud with both Dr Elephun and Mr Pompous, and frequently engages in volatile arguments with them. While arrogant, cantankerous and downright rude, he eventually comes to respect Astro's courage and abilities, even calling for his assistance in particularly difficult cases. Partnered with Chief McClaw, he first appeared in Episode 2: Colosso.

Police Inspector Nakamura (Nakamura-keibu; "Chief McClaw") - The chief of the police and the partner of Inspector Gumshoe. Played mainly for comic relief, he was normally portrayed as fat, dim-witted and gullible; a stereotype "clueless flatfoot" of the period. Nonetheless, he instantly recognised Astro's good side and frequently stood up for Astro Boy against his bullying partner (as seen in Episode 23). He first appeared in Episode 2: Colosso.

Shunsaku Ban (BAN Shunsaku; "Albert Duncan") aka Hector (later Percival) Pompous in the first series, Mr. Mustachio (Higeoyaji; "Daddy Walrus") in the second - originally introduced as a private investigator in the first American dub, Higeoyaji played several roles in the Japanese strip series, including school teacher and martial arts expert. Like Dr. Elephun, Higeoyaji serves as a surrogate father for Astro and Uran, providing guidance and advice when necessary. While gruff and comically short-tempered, he harbours a deep admiration for Astro, seeing him as the son he never had, and even stands up to the formidable Inspector Gumshoe in the boy's defence. Higeoyaji first appeared in Episode 7: Zero, the Invisible Robot. In both the original comic strip and the second 1980's Japanese series, he was Astro's school teacher (in Naoki Urasawa's Pluto he has apparently been promoted to principal), and his nickname was Mr Mustachio or Daddy Walrus. In the 2003 remake, he is notably absent from Astro's school, working full time as a private eye and is also the uncle of Ochanomizu's assistant, Yuko Kisaragi.

Mama and Papa - Astro Boy's robotic parents. Mama is depicted as an idealized 1960s housewife. Sweet, kind and nurturing. She is entirely trusting of her son's impeccable nature, knows he would never deliberately lie or harm another being (as seen in Episode 20). In contrast, Papa is portrayed as something of a well-meaning blowhard, often jumping to conclusions and losing his temper over minor incidents. They first appeared in Episode 2: Colosso. In the Sankei Newspaper Astroboy manga series it is revealed that Mama was modified to resemble Dr. Tenma's wife who had died of a heart condition shortly after Astro was sold to the circus.

Cobalt (Kobaruto; "Jetto") - Astro Boy's cybernetic brother. His origins differ in the continuities of the manga & anime versions. In the manga he is an inferior copy of Astro created as a replacement by Prof. Ochanomizu when he mas missing & presumed scrap. In the anime version he was a defective prototype of Astro built by Dr. Tenma, then sealed within the ministry of science archives & later released. Jetto has abilities comparable to his brother's, but lacks Astro's intelligence and common sense. Clumsy, accident-prone and gullible, he is a constant source of trouble for Astro's family (and everyone else who crosses his path. Despite these problems, Jetto is often shown to be extremely kind hearted and loyal. In addition to the abilities that were copied from Astro, he also shares a kind of telepathic link with his brother that gives him the ability to sense when Astro is in danger & home in his location. He originally died a heroic death at the conclusion of the Midoro Swamp story arc in the Shonen Magazine serial version of the manga, but Tezuka later changed his mind & rewrote the ending for the paperback version so that he survived. He first appeared in Episode 84: Brother Jetto. In the manga, his name is Cobalt. After the original anime & manga series ended Cobalt fell into obscurity, largely due to the fact that Atlas was recast as Astro's "brother" in the 1980s anime, making Cobalt's role somewhat redundant.

Ken'ichi- Astro's classmate. He's the class president and also the smartest. He first appeared in the manga Episode, The Hot Dog Corps.

Shadow - A robot built by Doctor Tenma who happens to have all his skills and his knowledge about building robots. He built numerous robots including duplicate copies of Doctor Tenma's robots. Shadow did not appear to have a face but instead has a big eye sign marked on the face of his head. Doctor Tenma built Shadow after realising that he himself cannot keep up with Astro due to his humanity, so he builds a robot to spearhead Astro's development. He also built Pluto and The Blue Knight. Shadow was meant to help Doctor Tenma with his plan to convince all the robots from around the world to join them in order to create their own new world. When Shadow had succeeded in creating Robotopia which was inhabited by robots, Doctor Tenma decided that it was time for him rule it. However, Shadow turned against him and revealed that he had turned himself into a robot clone of Doctor Tenma. Shadow appeared in Astro Boy (2003 TV series)

The Blue Knight - A robot who used to work at a robot circus, repairing broken robots who lost in robot fighting matches. When he saw how badly robots were treated in the circus he decided to take action by helping them all escape but however he was caught by his human owner who happens to be the ringmaster of the robot circus. He was thrown out of of space for attempting to set all the robots free. He was later on found by Shadow who rebuilt him into The Blue Knight. He is known to be a hero amongst many robots for helping those who were treated poorly by humans. The Blue Knight tends to be cold and cruel towards humans especially those who mistreated robots. He doesn't listen to anything they say and doesn't care if he hurts anyone of them because of all the anger that he had in the past. The Blue Knight appeared in Astro Boy (2003 TV series)