A Mechasaur who appeared in Episode 5 of Getter Robo.
After watching a video of the Getter Machines combining, Emperor Gore notices that Musashi would have trouble combining into Getter 3. Using this knowledge, he unleashes Mechasaur Giga to call them out. Giga attacks a train that was coming through a tunnel, getting the attention of Professor Saotome. When Ryoma, Musashi, and Hayato arrive in their Getter Machines, they try to combine into Getter 3. But Giga shoots fire from both of his mouths and interrupts their combination. He then tries to hit Musashi in his Getter Bear. Professor Saotome orders them to combine into Getter 2 and to use Getter Divide to get away. Hayato, however, doesn't listen and tries to fight Giga. But Giga catches the drill and spews out fire from his mouth again. After a while, Professor Saotome puts Getter Robo into automatic and had it perform Getter Divide, allowing them to escape. Later, Giga is attacking another tunnel but with cars this time. When Ryoma, Musashi, and Hayato arrive, they combine into Getter 3, since it's the only form they have that can fit in the tunnel. Getter Robo and Giga fight each other until the Mechasaur uses his Mace Tail and knocks Getter Robo to walls of the tunnel. With his back turned though, Musashi fires the Getter Missiles, making Giga flinch and accidently hitting a wall with water behind it. The water has an effect on Giga, so Ryoma figures out that it's weakness is water. So Musashi gets Getter 3 to throw Giga toward the wall and uses the Getter Missiles to cause the water to pour out all over Giga. After Giga gets flooded by the water, he is finally destroyed.
Fire Breath: Giga can shoot flames from both of his mouths. From his top head, the flames are green. But on the stomach, the flames are red.
Mace Tail: Giga has a mace on the tip of his tail that he uses for combat.