Subtitle: Huge Robot (巨大ロボット Kyodai Robotto)
- Height: 53 m
- Weight: 68 000 t
- Origin: Space
Giant Robot Zero was created and controlled by Anti Go-Ne to destroy a experimental super rocket created by PAT. When he first appeared at the test site, PAT tried to destroy him by electrocuting and bombing him but to no avail. PAT then attacked him in their planes but the robot showed no reaction to the attacks and even caught Jet Condor in his claw. Naoki, who had arrived in his plane to deliver some parts for the experiment, transformed it into Jumborg Ace and knocked Jet Condor out of Giant Robot Zero's grasp. He then shot the Handy Ring Flaser at him, damaging his right hand and causing him to retreat.
Later, Giant Robot Zero was unleashed again and once more, PAT's attacks proved useless against him. He fired missiles at the rocket launcher and it went up in flames. Jumborg Ace arrived and shot the Handy Ring Flasher at Giant Robot Zero. He then proceeded to chop off both his horns and shot the Beam Emerald at him. The mecha first sparked, and then exploded.
- Design: Yoshiaki Yoneya
- Giant Robot Zero's suit, except for his head, which was newly made, was modified from the Mirrorman kaiju Noah.
- The word "Zero" was added to his name to differentiate him from Toei's tokusatsu mecha Giant Robo.
- Powers and Weapons
- Arms: Giant Robot Zero has a couple of weapons concealed inside his arms. They can be used by choice.
- Destruction Rays: He can use cannons to shoot rays that can create massive sized explosions.
- Claws: He can use a large claw to grab objects. It is strong enough to stop flying objects.
- Drilling: By spinning quickly, he can drill into the ground.