Subtitle: Super Deadly Monster (スーパー必殺怪獣 Sūpā Hissatsu Kaijū)
Demagorg is a video game monster created by a boy and is secretly controlled by the Alien Chern. The Chern made a video game called "Giant Monster Coliseum" which features Demegorg as one of the characters another can create. The Chern then used children as test subjects as part of their plan to use one of the Children-Made monsters to destroy Earth by having them play and win matches. The boy who created Demagorg eventually won the tournament (with his last foe being Grossyna II), and the aliens gave him the grand prize of the win: the second version of the game, where he finds out that Dyna has been added as an enemy. Using Demagorg, he beats Dyna as well as the game, making Chern's test a success and Demagorg was unleashed into the real world and is under the boy's oblivious control, as he is wearing a headphone attachment to the game that is actually controlling his brain and forced him to do some actions. Super GUTS tried to attack Demagorg but the monster's adaptation to attacks proved their efforts futile. Asuka transformed into Ultraman Dyna and tried to fight, but thanks to the boy's gaming skills, Demagorg was now completely adapted to Dyna's powers. With the fight one-sided, Demagorg continued his onslaught on Dyna, stabbing him a few times with his tail and making Dyna's Color Timer blink.
Just as Demagorg is about to finish off Dyna, Super GUTS finds the video game and destroys it. This causes Demagorg to malfunction, no longer under the control of anyone. Berserk, Demagorg slammed into his creators' headquarters, killing them and unintentionally rendering Demagorg completely powerless. With the opportunity, Dyna goes into Miracle Type and fires the Revolium Wave at Demagorg, striking him in the chest and sending him to another dimension.
- Suit Actor: Koji Mimura
- Demagorg may have been inspired by Primal Rage, or Mortal Kombat as Demagorg's devouring ability resembles the fatality system, featured in both games.
- Demagorg started off as a red Tyrannosaurus, but the more opponents he defeats in the game, the bigger he grows. After reaching level 99, Demagorg gains his suit of armor.
- Demagorg's Tyrannosaurus motif was taken into account by request of director Takashi Kodama.
- The battle between Demagorg and Grossyna II, as well as against Ultraman Dyna, were actually green screens and poorly rendered stop-animation pictures; as the CGI graphics were unable to convey a high-quality picture during that time.
- The reason of Demagorg being part of a 3D video game is most likely due to the fact that during the year 1998 (this episode's airing year), various video game companies, such as Sega, Sony, and Nintendo all released powerful 3D video gaming systems that year.
- His name is a play of an English word Demagogue.
- Height: 68 m
- Weight: 72,000 t
- Origin: Giant Monster Coliseum
- Weakness: Demagorg's energy is connected to the video game Giant Monster Coliseum. Should the game or system be destroyed, Demagorg will become berserk and powerless.
- Powers and Weapons
- Satan Gorg Tail (サタンゴーグテール Satan Gōgu Tēru): Demagorg's tail is tipped with a sharp point he can use to impale enemies.
- Dema-Hand Protection (デマハンドプロテクション Dema Hando Purotekushon): Demagorg can increase the size of his hands so they're the size of himself. When he does this, he can protect himself from stronger attacks.
- Jaw Strength: Demegorg's tyrannosaur jaws are strong enough to grab enemies, hurl them in the air, or throw them at far distances.
- Devour: If an opponent is low on power, Demagorg can suck them into his mouth, even if they're his size, to increase his strength.