"Oh, such a nice and emotive form. Now, to put it in motion. Instance Abreaction!"
- ―Alexis before breathing Ghoulghilas to life.
It is later revived as Mecha Ghoulghilas (メカグールギラス Mecha Gūrugirasu).
- Ghoulghilas: High-Spirited Monster (気炎万丈怪獣 Kienbanjō Kaijū)
- Mecha Ghoulghilas: Counterattacking Monster (捲土重来怪獣 Kendo Jū Rai Kaijū)
After a Special Dog meant for Yuta Hibiki accidentally gets knocked over by the class volleyball team, Akane Shinjo crafted a small yet realistic-looking Ghoulghilas figure for Alexis, who used his Instance Abreaction to turn it into a real monster.
Rampaging through town, it destroyed everything in its path, including Yuta and friends' school. Its main target was Sakiru Tonkawa, Kena, Toiko and two other volleyball members, successfully targeting their house. It was not until Gridman arrived that it met any resistance, but at first it easily dealt with the giant due to Yuta's inexperience. After receiving a strategy from Rikka Takarada and Sho Utsumi via the Junk computer, Gridman rose again and targeted its weak spot, the neck. After tearing its head off and revealing its cybernetic innards, Gridman destroyed the beast's remains with the Grid Beam.
However, the next day, everyone forgot about Ghoulghilas except for Yuta, Utsumi and Rikka. Unfortunately the deaths of all five volleyball members were irreversible and they were rewritten to have died even before their entrance into high school.
Ghoulghilas later returns as an enhanced version of itself; Mecha Ghoulghilas, revised by Akane to ruin the Culture Festival at her school and to kill Gridman. As the day of the festival drew closer, the Gridman Alliance tried to convince Akane not to unleash Mecha Ghoulghilas, but their attempts failed. With no other choice, Gridman was summoned, but he appeared before Mecha Ghoulghilas did, prompting an evacuation. Akane then sent Mecha Ghoulghilas but despite its upgrades, it was no match for Full Powered Gridman, who once again tore its head off and then finished off the monster with the Grid Full Power Finish.
Both versions of Ghoulghilas, along with all the other Kaiju Gridman fought, reappeared when they were summoned by Alexis to get rid of Gridknight, since Akane refused to make any more new kaiju. Ghoulghilas was finished off by Gridknight's Gridknight Storm but Mecha Ghoulghilas gave Gridknight some trouble. It was later destroyed by Full Powered Gridman and Gridknight.
- Designer: Shinji Nishikawa
- Ghoulghilas' body shape was inspired by Femigon's.
- In Katakana, Ghoulghilas (グールギラスGilarus (ギラルス Girarusu) with extra letters left, the first Kaiju from the original series. ) can be rearranged into
- Ghoulghilas getting a 'Mecha' upgrade is a callback to the various Mecha-enhanced Kaiju from Denkou Choujin Gridman.
- Mecha Ghoulghilas' top piece resembles that of King Joe's. Its armored parts are also colored similarly to King Joe's Pedanium armor.
- The way Mecha Ghoulghilas' head armor closes up to form a drill is reminiscent of the Ultra Kaiju Gabora.
- Like Anti's, Mecha Ghoulghilas' Japanese subtitle cannot be accurately translated into a few words without losing some of its meaning, which is "to recoup one's strength for a renewed attack".
- Height: 70 m
- Weight: 50,000 t
- Weakness: Ghoulghilas' neck is incredibly frail, as a minor attack there from Gridman was enough to sever its head from its body.
- Powers and Weapons
- Fireballs: Ghoulghilas' signature ability to fire bursts of fireballs from its mouth. These are destructive enough to destroy entire buildings in one shot. They can also bounce off the ground for additional distance rather than exploding immediately.
- Headless Life: Ghoulghilas can seemingly survive for a while after having its head removed, although it presumably can no longer use its fireballs without its mouth.
- Height: 72 m
- Weight: 60,000 t
- Powers and Weapons
- Flamethrower: Instead of fireballs, Mecha Ghoulghilas launches a stream of flames from its mouth.
- Guns: On its back are four guns that it uses to shoot with.
- Drill Head: The armored plates on the sides of its head can close up to form a drill, and the entire head and neck spins at a high speed.
- Tail Drill: Mecha Ghoulghilas has a drill on its tail, though it was never used.
- Headless Life: Like its original form, Mecha Ghoulghilas can continue to function after having the head removed.