"The path to glory is open anew...! Space-Time Destroyer God Zegan!"
- ―Alien Shadow Kuruto after summoning Zegan.
"Kam Tatahl Shadow. Space-Time Destroyer God Zegan!"
- ―Activation/piloting command for Zegan.
Subtitle: Dimensional Demolition Lord (時空破壊神 Jikū Hakai-Shin lit. Space-Time Destroyer God)
Through years of research, the Alien Shadows managed to construct this bioweapon that was to be used to invade the Earth in order to take it over so that they can replace their planet, which had been deserted after the devastation caused during the war with Belial. The means to summon and control it was in the hands of the AIB Agent Zena who was on Earth, who intended to destroy it eventually, but decided to leave in case of a worse case scenario involving Belial and locked the device used to summon him in a pocket dimension.
Much later, Zena's student named Kuruto made use of this creature, entering it to control it directly, but had to face off against Geed and Zero. Their battle led to a beam clash with Zegan's Zegant Beam going against Geed Magnificent's Big Bustaway, their energies destabilized each others' beams and resulted in a dimensional portal that begun to suck everything in, even Moa Aizaki who was nearby. It was not until Ultraman Zero Beyond interfered that their beam clash ended, with each beam being sent right back to their user. Thus, Zegan was sent to another dimension by its own beam. Afterwards, a space-time distortion appeared in the combat zone and RE.M. revealed that the people and things that Zegan were actually in an area filled with forest shrouded by an interference shroud.
It didn't take too long, however, before Zegan's energy signature was detected again and Kuruto managed to summon Zegan back to the Earth, despite Zena's warning that using the kaiju's power would cost the life of the Alien Shadow, to reign destruction upon it once more by firing its Claw Lightning before he was once again confronted by Geed and Zero. Their rematch started when the two Ultras dodged the lightning and then striking at the kaiju with their Geed Claw and Zero Sluggers respectively. The two Ultras then held the upper hand with their agility and teamwork but Zegan fought back and ended up hurting Zero's wrist and electrocuting Geed before attempting and failing to send Geed to another dimension again.
Geed then transformed into his Magnificent form and used his Arrayzing Geed Barrier to push the Zegant Beam back, but it wasn't enough so Zero transformed into his Beyond form and summoned a similar barrier to push the remaining the energies back to Zegan, and eventually, the two Ultras pushed the barriers so close together, that they encapsulated the kaiju in a sphere as he still fired his signature beam all while Kuruto kept saying "Kam tatahl Shadow" and after a short while, Zegan finally met his end as well as Kuruto as they exploded in a fiery ball and the broken device was retrieved by Zena.
"Trying to trap me outside this dimension? It won't be that simple!"
- ―Belial Atrocious before destroying Zegan with his Atros Burst
During Belial Atrocious' raid on Earth, Zegan was reproduced and revived by Zena and the AIB to aid Geed and Zero in their battle. They devised a plan to trap Belial Atrocious in another dimension by allowing Zegan to engage in a beam clash with Geed. However, Belial saw through the plan and destroyed Zegan in one shot with his Atros Burst.
- Suit Actor: Hiroyuki Arai
- Zegan's motif is a mixture of aquatic creatures, such as: Sharks, Killer Whale, and crustacean animals.
- Zegan's design is similar to Lagoras, as shown by the similarities of their heads. At this time, it is unknown whether it is a modified Lagoras suit, or if it is a newly created suit.
Zegan reappeared as part of a monster auction, having been summoned by Alien Magma to demonstrate his power by making it fight the mother of a Zandrias baby and held the advantage despite the mother's efforts. Upon Hellberus' arrival however, Zegan was destroyed by the kaiju when it stabbed Zegan in the chest with its tail.
- Height: 58 m
- Weight: 47,000 t
- Origin: Planet Shadow
- Maximum Flight Speed: Mach 3
- Underwater Traveling Speed: Mach 3.8
- Underground Traveling Speed: Mach 1
- Brute Strength: 100,000 t
- Grip Strength: 54,000 t
- Powers and Weapons
- Zegant Beam (ゼガントビーム Zeganto Bīmu): A blue laser fired from Zegan's chest. This beam first makes an object explode, before creating a small interdimensional portal that sucks in the explosion and object, as well as anything within its vacuum. If in a beam lock with an opponent, the two beams will spiral and converge into a giant interdimensional portal/black hole above them.
- Interdimensional Gate: When summoned, Zegan appeared as though swimming through a mass of mist. He can swim through the mist, as if it was much deeper.
- Claws: Zegan's hands are crab-like claws that can be used to grab or strangle opponents.
- Scissor Blaster (シザーブラスター Shizā Burasutā): Zegan's claws can also fire out red lightning waves.