Umataro Tenma (天馬午太郎, Tenma Umataro) more commonly called Dr. Tenma. Is a recurring major character in the Astro Boy series. He is a legendary robotics engineer and a PhD. graduate from Nerima University. Tenma gained widespread fame for developing the Bewusstsein AI with his roommate Hiroshi Ochanomizu. Later in his career he becomes the Minister Of Science and creates Astro, a robotic boy with human emotions and the first robot using the Kokoro AI after the sudden death of his son Tobio Tenma in a car accident.



Umataro Tenma has a pointy nose, a short beard, and long curly hair that leans forward. Doctor Tenma is Usually seen with a lab coat on. He is also shown briefly during the manga in "The Greatest Robot in The World" with sunglasses on.


He is often neglectful to his son, and after his son's death is obsessed with rebuilding him into a robot. He is initially kind and happy with Astro, but once he realizes he will never grow, he spirals into hatred and frustration of the robot, even going so far as to hit him with a broom or shovel. Once Dr. Ochanomizu takes Astro in, Tenma is obsessive with getting Astro back. He often ignores Astro's feelings and is capricious when his plans are foiled- he will apologize for his actions in one chapter, then attempt to get Astro back to him in another. However, in the manga chapter, "The Greatest Robot on Earth", Tenma and Astro appear to be on good terms with each other, and Tenma upgrades Astro to have one million horsepower.


Captain Atom

In his very first appearance in the 1951 short series Captain Atom, Dr. Tenma is a robotic engineer who previously lost his son, and is part of the research staff looking into the space people. Both he and his space lookalike have lost their son, and they become extremely envious over the robot Tobio. This leads to Tenma killing his space version with a shrinking solution, and commandeering the movement against the space people in an attempt to gain back his son.

Astro Boy

In most versions of the manga, Dr. Tenma is busy with the Ministry of Science, and either by his neglect or pure accident, his son is killed in a car accident. Tenma creates a robotic version of his son, but gets tired or frustrated with it; he usually winds up selling him to Hamegg, the owner of a robot circus.

In various chapters, Tenma briefly appears in disguise to protect Astro ("Cleopatra"), and at one point tries to steal Astro back. He only retreats from attempting to take back Astro in the chapter Meeva. It is the aforementioned pair of chapters that influenced the 2003 version of Tenma.

In the time traveling arc of the manga, Tenma's wife is alive and living with him. Tobio's death and reproduction is all the same, except Tenma's wife plays more of a part in trying to get the robot Tobio back from the circus, before divorcing Tenma and dying.

In Other Media

Comics and Manga

The Original Astro Boy

In the 1987 comic series, Dr. Tenma is known as Dr. Boynton, and again loses his son Astor in an accident and rebuilds him as a robot. However, Boynton is far more dangerous than his previous incarnations. He is violent to Astro, at one point putting a robot bomb spider in Astro to control him. Boynton used under-the-table money from the military to build Astro, packing him with weapons, and then sells Astro to the robot circus when he becomes afraid of Astro.


Dr. Boynton in issue #8.

He was once married to a woman named Jean, who divorced him before Astor's accident, and may have committed suicide after Boynton begun trying to make a robot Astor. This has negatively affected his mental health; Boynton in this version has extremely strong paranoia, to the extent of hallucinations and thinking people are after him. He retreats from society, and attempts to help guard Astro from afar.


1963 Television Series


In the 1963 anime, Dr. Tenma loses his son in a robot car accident, and immediately advances the Ministry of Science's attempt to make a humanoid robot. He succeeds, creating a replica of his son, and takes him as his son. After some time, Tenma becomes increasingly frustrated with the robot Tobio's inability to grow taller, and sells him to Ringmaster Hamegg.

Tenma appears in only a few other episodes after this, in one instance appearing briefly to assist Astro like in the manga, and in another to plead with Astro to come back to him.

Jetter Mars


known as "Mr.Tenma," he appears in Jetter Mars having the role of a grieving man who had lost his wife and only son in a car crash. Afterwards, he moved into a small ranch. Upon seeing Jetter Mars wandering around his property, he saw that Jetter Mars resembled his lost son Tobio, he then donned a knights armor and saved Mars from a trap Jetter Mars fell into. Mars, not being the brightest tool in the shed, thought the Knight was a rather weak robot, then Mr. Tenma still donning the knight armor, pretended to have lost a lot of energy and requested some from Mars. However, Mars energy was drained almost entirely. Upon hearing this, Mr. Tenma revealed himself to be a human, shocking Mars, who realized too late that it was a trap and then shut down. Later a group of gangsters arrived and Mr. Tenma tried to work with the gangsters to have Mars remodeled to appear more like the deceased Tobio, however, shortly afterward, the gang leader betrayed him saying he would rather steal Mars and kill Mr. Tenma. A character named Adios appeared in time to prevent Mr. Tenma's death and forced the gangsters to restore Mars energy.

1980 Television Series



In the 1980 series, Dr. Tenma is constantly busy working at the Ministry, struggling to create a humanoid robot. Skunk Kusai comes to Tenma's house to promote the Omega Factor, which Tenma turns down, offending Skunk. Tobio then suggests that Tenma create a robot that looks like a child. This is more successful to design, but this leads to Tenma being too busy to take Tobio to the zoo. Tobio tries to leave on his own, and gets into a fatal traffic accident. On his deathbed, Tobio asks Tenma to treat the robot like he would treat him.

The robot is declared too dangerous, with a public official ordering Tenma to shut down the project. However, Tenma sneaks into the Ministry of Science and activates the robot, renaming him "Tobio" and raising him in secrecy at home. Several fiascoes ensue with Astro's newborn robotic mind, including when his mind links with Atlas's from afar. The attempt to shut down a stunned Astro leads to Tenma going to the hospital. There, Tenma promises Astro that they'll go on a cruise to get away from the city, most likely to hide Astro's existence.

On the cruise, Astro embarrasses himself and Tenma during a dinner meeting, and Tenma tells Astro to leave him alone. Astro sadly wanders the ship, and winds up fighting Atlas, stopping an iceberg collision, and signing a contract to Hamegg. While Astro is convinced that Tenma has disowned him, Tenma is last seen searching the ship for Astro. Tenma is not in any other episode again, but fans assume that he either died from a heart attack during the search, or moved away.

His best friend is his coworker Ms. Honda (Ms. Ford in the American English dub), and at one point consults her for help with the robot Tobio. In the American English version, Tenma is renamed "Dr. Boynton," and in the Canadian English version, is renamed "Professor Balfus."

The Last Mystery of the 20th Century

The Last Mystery of the 20th Century is a special, in this special Osamu Tezuka is invited to a new years party in a mansion owned by Dr. Tenma, when Osamu Tezuka suddenly disappears it's up to his most popular characters to find out what happened to Osamu Tezuka and find him before the other guests arrive. Alongside Dr. Tenma, Dr. Ochanomizu, Hamegg, and Higeoyaji also appear in this special.

2003 Television Series

Dr. Tenma is more central a character than ever in the 2003 series. He is the central villain of the series, and causes an enormous amount of conflict throughout the series. He and his robotic double Shadow create Pluto, initiate a robot war, indoctrinate the Blue Knight into Shadow's cause, freeze a large portion of the city, and almost kill any number of Metro City citizens. Tenma is an open misanthropist, only caring about getting Astro back as his son. At one point, he comes to hate being human so much that he almost converts himself into a robot overlord.

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He lives in a rundown gothic building not too far from the Ministry of Science, working commission on robot production. Through this business, he winds up building Atlas, and briefly bonding with him as a dysfunctional father-son duo. Tenma is only accompanied by an army of robotic dogs, which can be converted into weapons and flying vehicles.

Before the main story of the 2003 anime, Dr. Tenma was the Minister of Science. He was usually too busy to be around his son, to the point of sending assistants to go with Tobio to sporting events, and giving Tobio a robot guardian named Robita. He attempted to make things up to Tobio with monetary items and gifts, at one point giving Tobio a jetbike. Shortly after, he took Tobio to the Ministry's robot disposal area as part of an offer to replace Robita with an entirely new, updated robot. Tobio was so disgusted with the idea of losing his friend that he ran away. Not long after, Tobio died on impact from a truck.

Tenma was distraught and feeling guilty, and created a robot replica of Tobio, retreating from the public and raising the robot Tobio in private. However, after Tenma took Astro to the same robot disposal area in the Ministry as before, Astro rebelled and smashed a conveyor belt. This caused Tenma to electrocute Astro, stow him away, and burn down his lab.

Atom: The Beginning


Astro Boy (2009)

In the 2009 CGI film by Imagi, Bill Tenma is voiced by actor Nicolas Cage,[1] and loses his son Toby in an accident where Toby is locked in with a berserker robot. Tenma, with the assistance of Doctor Elefun, creates a robotic duplicate of Toby, later renamed Astro. He outfits the robot with advanced defence capabilities so that he can't be harmed. Then, he copies Toby's memories into the robot, hoping that Astro will be just like his real son. When the robot version begins to develop his own personality, Tenma tearfully rejects him.

After Astro Boy runs away, he is captured for the power source that Tenma used on him. It is to be extracted from him and put into the Peacekeeper. Astro encourages this decision, accepting that he could never live up to Tenma's expectations. Tenma, however, refuses to have Astro deactivated, saying, "You're not Toby, but you're still my son!" Tenma is less villainous and deranged in the film, becoming more of a returning father figure who takes back Astro as a son. He was partially designed after Nicolas Cage.

Voice Actors

Robots created by Dr. Tenma


  • The literal translation for Tenma is "heaven horse", or "pegasus."
  • According to his horse pun filled official profile in the Captain Atom chapter, Tenma was born into a long line of horseradish farmers. His first name "Umataro" is a combonation the Japanese word "uma"-horse and taro, a suffix for Japanese male names.
  • In Captain Atom, the manga, and the 1987 comic, Tenma is an alcoholic.


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