Subtitle: Space Steel Dragon (宇宙鋼鉄竜 Uchū Kōtetsu Ryū)
- Height: 65 m
- Weight: 78,000 t
- Origin: Planet Desimo → Kunrun Mountains
Guwam was a monster who had come to invade Earth as a weapon by Alien Desimo. After being attacked at an air base, both monster and master had been forced into sleeping for 24 years that their current locations, with Guwam asleep in the Kunrun Mountains. After Alien Desimo had found a host in the form of Rena of GUTS, The alien merged with Guwam, awakening the monster and sending it to attack GUTS, who had appeared at the Mountains to investigate. Guwam immediately began releasing its Smoke to make Earth's atmosphere more suitible to its master, all while GUTS was unable to penetrate his armor with their weapons. Shortly after, Ultraman Tiga arrived by teleporting to Guwam's location and stopped GUTS from striking at Guwam's exposed head in fear of them killing Rena. However, taking GUTS's weapons head on wound up weakening Tiga and allowing the Ultra to be pummeled by Guwam. Tiga however would not give up and managed to free Rena from Guwam's control, allowing GUTS to fire their Dexus Beam at the monster's head, destroying both Guwam and Alien Desimo simultaneously.
- Despite looking robotic, Guwam was proven to be a cyborg, as seen when a life signal was detected from it.
- Guwam's roar is used for every monster in the video game Ultraman Tiga & Ultraman Dyna: New Generations.
- Guwam is one of the few monsters to be defeated by a GUTS weapon.
- Interviews with the "Ultraman Tiga" staff and writer showed that Desimonia and Guwam were all creations of Alien Desimo.
- Guwam's suit was modified from King Molerat.
- Guwam's name comes from Wyrm, a type of dragon from British and Norse mythology and shares one of their common abilities of spewing a gas toxic to humans.
- Powers and Weapons
- Atmospheric Remediation Gas (大気改造ガス Taiki Kaizō Gasu): Guwam can exhale a red smoke from its mouth. It's purpose is to transform air into a more suitable living condition for Alien Desimo and also highly toxic to humans.
- Armor: Guwam's armor is strong enough to repel weaker projectile attacks of his body.
- Weakness: Guwam's head is the only part of his body that is not protected by his armor. Also, it seem that Guwam can't move, which makes him less mobile. Guwam also has very few offensive techniques.