This list covers the characters from SSSS.Gridman , SSSS.Dynazenon , and Gridman Universe by Studio Trigger in the Gridman Universe, a fictional world created by Tsuburaya Productions.
Gridman Alliance (グリッドマン同盟, Guriddoman Dōmei) is a trio of high school students who are the protagonists of SSSS Gridman, helping the Hyper Agent Gridman battle the Kaiju attacking their city. Due to their connection with the hero, they were the only ones who are not affected by the changes made when one of Akane's Kaiju killed a victim, causing them to be erased from existence. Their base of operations is Junk Shop Aya, Rikka's shophouse.
The NGJHS, short for Neon Genesis Junior High Students (新世紀中学生, Shinseiki Chūgakusei, Lit "New Generation Junior High Students"), is a quartet of Hyper Agents who pose as youths dressed in black. They are later revealed to be embodiments of Gridman's scattered fragments modeled after his memories and became living beings in their own right. This factor plays in their Assist Weapon (アシストウェポン, Ashisuto Wepon) forms being able to combine with Gridman and increase his power, initially one at a time before their power output is reduced so they can all appear and form Full Powered Gridman. But when Gridman is absent, the Assist Weapons can combine on their own into War God Combine Powered Zenon (合体戦人 パワードゼノン, Gattai Senjin Pawādo Zenon). In contrast to the agile Gridman, Powered Zenon relies on strength and its signature move is Powered Breaker (パワードブレイカー, Pawādo Bureikā). During the events of Gridman Universe, joined by Rex, the Assist Weapons gain the ability turn into a purple version of their Powered Zenon form called Powered Knight Zenon and combine with Gridknight to form Full Power Gridknight.
The protagonists of SSSS Dynazenon.
A pair of Kaiju in human form who appeared in SSSS Gridman, During the events of Gridman Universe, Both of their younger and older selves to exist as separate entities until they were sync to fight Mad Origin.
The Kaiju Eugenicists (怪獣優生思想, Kaijū Yūsei Shisō) are a quartet of youths that serve as the antagonists of SSSS Dynazenon. Five thousand years prior, they were betrayed and killed by Gauma when he sided against them after they attempted a coup against their nation. Having been resurrected in the present day by their link to the Kaiju, the Eugenicists use their Instance Domination (インスタンス・ドミネーション, Insutansu Dominēshon) ability to take control of Kaiju so they can destroy humanity. After the death of Garnix and the discovery that no new Kaiju will ever be born again, the Kaiju Eugenicists disband and go their separate ways. In the last episode, however, they choose to be absorbed into Gagula to increase his power for his battle with Kaizer Gridknight, existing within it in a very similar way to how the pilots appear within Dynazenon. They are apparently killed after the death of Gagula, though Shimizu is seen afterwards in an indeterminate space.
Mad Origin (マッドオリジン, Maddo Orijin) is the main antagonist of Gridman Universe and is referred by Alexis as a Cluster of Kaiju origins (怪獣発生源の集合体, Kaijū hassei-gen no shūgō-tai), an intelligent Kaiju that embodies the worst of humanity and can speak human language through a monster generator built into his chest. Mad Origin interferes from outside Yuta's universe as part of his plan to cause a Big Crunch, seeking to plunge all reality into primordial chaos. However, Akane’s return forces Mad Origin to personally battle the protagonists, able to fully counter Gridman and Gridknight’s attacks. But Alexis’s sacrifice allows Gridman and Gridknight to defeat Mad Origin.
Giant monsters that born the emotional states of humans, described by Sizumu in SSSS Dynazenon as embodiments of humanity's disillusionment from being restrained by emotional bonds. While most encountered are aggressive and embody humanity's negative emotions, there are those like the GridKnight Alliance and Golburn who are exposed to humanity's positive traits and become allies.
Created from Akane's models through Alexis Kerib, these Kaiju are each a reflection of Akane's mental state. The Poison Gas Monsters that surround Tsutsujidai repair any damage done to the city following a Kaiju attack while altering peoples' memories of any casualties. When Akane fell into a depression following her stabbing Yūta, Alexis recreates all the Kaiju for a final attack on Tsutsujidai. But Gridknight and the Gridman Alliance destroy the Kaiju army.
The Kaiju that appear are sought by the Kaiju Eugenicists, who seek to control them and use them to wipe mankind out. Upon being controlled by a Kaiju User's Instance Domination, they grew into red-eyed behemoths that towered over the cityscape, though Zaiohn grew massive without any outside influence.
Kaiju created by Mad Origin to aid his plans. Like Mad Origin, their names are close anagrams of Gridman's name.