Astro Boy is based on Tetsuwan Atom (Mighty Atom) created by Osamu Tezuka. The Tetsuwan Atom Manga (1951 to 1968) was made into Japan's first black and white animated television series. It debuted on January 1, 1963. In all there were 193 episodes. In September 1963 Astro Boy came to American television (NBC). NBC stopped showing the series (at the 104th episode) in 1964. Two more completed series were released. Astro Boy - 1980 (in color) and Astro Boy - 2003 (in color). The Japanese Mighty Atom ends at episode 193 with the death of Atom. Atom dies when he flies a bomb into the Sun to save Earth.

Atom (Astro) is created in the year 2003 (2000 in the U.S. release) by Professor Tenma (Boynton), after his own son Tobio (Astro/Toby) is killed in a car accident. Tenma becomes disappointed and upset with Atom, his Tobio-substitute, and sells Atom to Hamegg (Cacciatore) the ring-master of a robot circus. Professor Ochannomizu (Elefun) rescues Atom from the circus and adopts him.