Getter Robo (ゲッターロボ, Gettā Robo?, typically romanized as Getter Robot in the various manga) is a Super Robot manga series created by Go Nagai and Ken Ishikawa, as well as an anime series produced by Toei Animation. The series was broadcast on Fuji TV from April 4, 1974 to May 8, 1975, with a total of 51 episodes. Getter Robo is often credited as the first combiner robot in anime history, although the Astroboy series featured combining robots in a few episodes in the previous decade.

Source: Wikipedia