Subtitle: Violin Terrible-Monster (バイオリン超獣 Baiorin Chōjū)
Geegon was a Terrible-Monster created by Yapool after a boy named Haruo who tried to destroy his own violin after getting into an argument with his strict mother. Taking the form of Haruo's violin, the violin began playing itself, stealing the soul of Haruo and a girl. The Cello then flew around the city, slowly stealing the souls of anyone who listened to his playing, growing bigger by the minute. Finally upon growing big enough, the violin began to playing in the heart of the city, stealing even more souls to empower it. After a scuffle with Haruo's mother, who willing put herself under the violin's influence, Hokuto and TAC opened fire at the giant violin. However, this finally unleashed Geegon's true form, who attacked back and downed TAC's jets. Hokuto quickly transformed into Ultraman Ace to battle the violin Terrible-Monster, but Geegon had stolen so many souls and was able to overpower Ace both physically and with the aid of his supersonic attack.
After striking Ace with his lasers, Ace was briefly paralyzed by the Terrible-Monster, but thanks to Earth's sunlight reaching him, Ace fought back and this time severely weakened Geegon by severing the strings that created his music. With Geegon mortally wounded, Ace destroyed the Terrible-Monster with the Metallium Ray. After being killed, Geegon faded away in the form of music, returning all the souls he had stolen.
- While Geegon's body is completely new, his face is a modified Kaimanda beak.
- Geegon's roar is a Sadola roar played backwards.
- Height: 51 m
- Weight: 43,000 t
- Origin: Yapool's Dimension
- Powers and Weapons
- Violin Form: Geegon can transform into a giant violin. When like this he can fly and steal souls.
- Soul Steal: While in violin form, the music played by Geegon can steal the soul of anyone who listens to it. The more souls he steals, the more bigger and powerful Geegon becomes.
- Supersonic: Geegon can emit a loud and painful, high-pitch sound by shaking his body.
- Lasers: Geegon can fire 4 green lasers from the pegs on his head, they can cause medium explosions. If striking an opponent, they will be paralyze for a few seconds.
|Ultraman Ace Kaiju|
|Verokron | Yapool | Chameleking | Vakishim | Garan | Aribunta | Giron Man | Brocken | Alien Metron Jr. | Doragory | Muruchi II | Gammas | Zaigon | Alien Antira | Unitang | Sabotendar | Baraba | Ace Killer | King Crab | Cattle God | Cowra | She-Devil | Hotarunga | Black Pigeon | Android Couple | King Kappa | Zemistlar | Aprasar | Aprasar Fairy | Space Mask | Black Satan | Giant Yapool | Mazaron Man | Yojo | Mazarius | Alien Orion | Sphinx | Alien Hipporit | Lunaticks | Undergroundmon | Gitagitanga | Red Jack | Baktari | Coakes | Bad Baalon | Kaiteigagan | Dreamgillas | Soundgillar | Machless | Snowgiran | Namahage | Alien Fire | Firemons | Alien Steal | Kaimanda | Shishigoran | Iceron | Woo II | Fubugirara | Onidevil | Gasgegon | Daidarahoshi | Hanzagiran | Verokron II | Yapool Woman | Univerlages | Aquarius | Alien Revole | Signalion | Geegon | Alien Simon | Jumbo King|