Gigantor (originally Tetsujin 28-gō 鉄人28号, literally Iron Man #28) was a manga by Mitsuteru Yokoyama published in 1958 which was later made into several anime series, the first in 1963. It was the first "giant robot" series. A live action motion picture with heavy use of computer generated graphics was produced in Japan in 2005 based on the old comics as opposed to the newer version in "New Gigantor" which was translated into many languages including Arabic.

There are many indications that Gigantor is a predecessor to another "retro-style" anime, Giant Robo, including the main characters' design/personality similarities.

Cartoon Network's Adult Swim aired the original English version at 5:30 AM (Eastern and Pacific) from Monday/Tuesday overnight to Thursday/Friday overnight, and Saturday/Sunday overnight. It is shown on this block perhaps due to its violent nature for a children's cartoon, and often "comical" portrayals of villain deaths. But others believe it is to attract the adults who once watched this series during its time back in 1968. (Wikipedia)