Dr. Tenma , whose real name is Umatarō Tenma is also known as Dr. Nagamiya Tenma, Dr. Boynton, and Dr. Balthus, is the father/creator of Astro Boy in the anime and manga series of the same name created and animated by Osamu Tezuka.

Tenma means Pegasus and is literally translated from Japanese as Heaven-horse. In the 2003 series, he is very cruel. He also admits that he was a down beat dad.

When Tenma's nine-year-old (thirteen-year-old in the 2009 feature film) son Tobio (Toby in the 1980s and the 2009 feature film; Astor in the 1960s) dies in a car accident (robot testing accident in the 2009 feature film), he decides to recreate him as an invincible robot. After living happily for a while with the child robot, Tenma realizes that an artificial child can not replace his son, particularly when he acknowledges that the robot will not grow like a normal child. So, he sells the robot to Hamegg, a robot salesman. The robot eventually ends up performing in a circus. It is here where he is found and adopted by Professor Ochanomizu, who turns him into Astro Boy.
200px-Dr Tenma

Tenma realizes that Astro is amazing and, even though his affection towards the robot begins to return, he knows he can never make amends for his behavior. Still, he helps Astro frequently. He builds robotic parents for Astro, enhances Astro's power to one million horsepower (700 MW) when he fights Pluto, rescues Astro from a Cleopatra robot, and rebuilds Astro after he is destroyed while trying to protect Blue Knight.

In the 1980 anime series, Tenma does not really reject Astro. Instead, he dismisses him for causing a mess at a boat dinner, after reminding him he was a robot. Astro then gets kidnapped by corrupt circus ringmaster Hamegg, while Tenma tries to get Astro back. The circus is not as harsh and Hamegg not as evil as in the original manga version. Professor Ochanomizu, with his assistant Chiyoko, notices Astro and tricks Hamegg to save the child robot.

Dr. Tenma abandons both Astro and the Ministry in a fit of insanity, after Astro rebels against Tenma's cold behavior in destroying old robots [he even liked raw salmon]

Later, when Tenma witnesses Astro's heroics, he begins to believe that Astro will be a Messiah figure. He believes that Astro will lead robots to equal standing with humans or he will help them overthrow or kill all humans. (The latter belief gradually takes over as the series progresses.)

Prior to Astro's first battle with Atlas, Tenma constantly calls Astro as Tobio, the dead son he was supposed to replace. He only recognizes him as a separate entity once Astro corrects him.

It soon becomes apparent to Tenma that he himself cannot keep up with Astro due to his humanity. So, in order to keep up with Astro, he builds a robot to spearhead Astro's development. This robot is appropriately named Shadow and is eventually revealed to be a robot double of Tenma himself.

In the end of the 2003 series, Astro is very badly damaged and Tenma rebuilds him, minus his memories. Astro, however, rejects Tenma a third time for his cold attitude. Because of this, Tenma attempts suicide but is saved by Astro, who explicitly forgives him. Tenma still loved Astro and wished he never shut him down in the first place

The series ends with Tenma admitting that he was a poor father, after which he is arrested. The final image of Tenma is of him in a jail cell, holding a photograph of his human son Tobio and a photograph of his robotic creation Astro. It is unknown if he was released from confinement, but it seems unlikely.

In the 2009 CG-animated feature film adaptation, Tenma, who is voiced by actor Nicolas Cage,[1], creates Astro Boy after his son Tobio is killed in a robot testing accident. (Tenma accidentally locks Tobio in the chamber with an experimental war machine called Peacekeeper.)

Tenma, with the assistance of Doctor O'Shay, creates a robotic duplicate of Tobio. He outfits the robot with advanced defence capabilities so that he can't be harmed. Then, he copies Tobio's memories into the robot, hoping the robot will be just like his real son. Tenma begins to feel that this robot duplicate is acting strangely. When he realizes that the robot is not really Tobio, he rejects him.

After the robot 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. The robot encourages this decision, accepting that he could never live up to Tenma's expectations. Tenma, however, refuses to have the robot deactivated, saying "You're not Tobio, but you're still my son!" Tenma is less villainous and less mad in the film. Instead, his personality is similar to that of the original manga. In the film, he reacts similarly as in the manga, realizing that Astro is not his son and rejecting him. However, he does not sell him to Hamegg. The major difference between the character of Tenma in the film and in other versions of Astro Boy is that Tenma comes to accept Astro. His first name is Bill instead of Umatarō in the movie.