Groizer X (Japanese: グロイザーＸ, Hepburn: Guroizā X) is an anime series aired from 1976 to 1977.

The anime was created by Go Nagai and Gosaku Ota as a side project during the time they were busy with the various Mazinger series.

The original Groizer X toyline are one of the very few Super Robot toys produced by Nakajima Manufacturing Company instead of the industry dominant Popy.

While not being a great success in Japan, Groizer X had a considerable impact in Brazil, where it was aired under the name O Pirata do Espaço ("The Space Pirate") in 1984/1986 at the Manchete Network.

In Italy it was one of the few robotic anime to be aired on Silvio Berlusconi's Canale 5, in 1981, where it failed to garner much following and was never replayed.