| Great Mazinger vs. Getter Robo G: Kuchu Daigekitotsu | |
| Director: | Masayuki Akehi |
| Producer: | Chiaki Imada |
| Screenplay: | Keisuke Fujikawa |
| Starring: | Akira Kamiya Jōji Yanami Keaton Yamada Keiichi Noda Toku Nishio |
| Music: | Michiaki Watanabe Shunsuke Kikuchi |
| Studio: | Toei Animation Dynamic Production Fuji Television |
| Distributor: | Toei Animation |
| Runtime: | 25 minutes |
| Country: | Japan |
| Language: | Japanese |
is an animated short film produced by Toei Doga. It is a crossover anime between Great Mazinger and Getter Robo G. It was originally shown in theaters along with Uchu Enban Daisenso. They both premiered in in Japan.
As with the rest of Toei's Mazinger Vs. animated films, the events presented in the film are not considered canon to either of the anime television series, but it is considered a direct sequel to the previous film Great Mazinger vs. Getter Robo.
Like most of the Mazinger movies, it was shown in some countries outside Japan where the TV series were broadcast. It is known as Il Grande Mazinga contro Getta Robot G in Italy, Gran Mazinger contra Getter Robo G in Spain and مازنجر الكبير يقاتل جيتا روب in the Middle East.
Aliens in a spaceship decide to conquer the Earth and begin by attacking the headquarters of the Getter Robo team while the Mazinger was being repaired so it could not go to their aid. One of the team members, Musashi, is killed in the battle with the alien monster Grangen and his vehicle is destroyed, meaning they can no longer form the first Getter Robo. However the laboratory already had a new Getter Robo ready for action named Getter Robo G and a new third pilot is elected. Meanwhile, Great Mazinger and his allies fight the invaders' giant robot Bong but it was just bait to lure it out so that the invaders could use their trump card: Pikadron. Getter Robo G arrives to help, but their combined beams only make Pikadron grow bigger. However Great Mazinger's pilot Tetsuya figures out how to strip this defense from the monster and destroys it with a new weapon. The alien spaceship is also destroyed and in the end everyone gets together to grieve the loss of Musashi.
There are three alien monsters that serve as the antagonists of the movie. They were created by the Mysterious Invaders, the same race that created Gilgilgan in the previous movie. In Go Nagai's Dynamic Heroes the aliens were referred to as the Damdom and were revealed to be the arch enemies of the Vegan Empire from UFO Robo Grendizer.