Gigantor is a 1963 anime adaptation of Tetsujin 28-go, a manga by Mitsuteru Yokoyama released in 1956. It debuted on US television in January 1966. As with Speed Racer, the characters' original names were altered and the original series' violence was toned down for American viewers. The dub was created by Fred Ladd distributed in the US by Peter Rodgers Organization.

Tetsujin 28-gō , known as simply Tetsujin 28 in international releases, is a 1956 manga written and illustrated by Mitsuteru Yokoyama, who also created Giant Robo. The series centers on the adventures of a young boy named Shotaro Kaneda, who controls a giant robot named Tetsujin 28, built by his late father.