Invictus Ultrarius, The Invincible One

Only legend and small talk from the Primordial Deities ever get around that this guy even existed, or if he even still exists at all. Powerful enough to where he can project the size of his body to appear at a much larger size than the Ultimorian Universe itself, it is quite possible that Invictus Ultrarius, The Invincible One, is the living personification of the Ultimorian Universe itself. None of this has been known to be confirmed, though, as only very recently was even a remote image of what Invictus even looked like was presented to Shiramu Inc. by Ultima when doing some mental testing on Ultima after a rough day. Aside from the fact we now know what Invictus looks like, and the fact he's real after all, it cannot be confirmed or denied that Invictus is capable of the many great feats established by the other Primordial Deities. In addition, nobody within Ultimoria even knows where the hell Invictus is; the entire universe has been, for the most part, fully explored. It is quite possible that Invictus is currently not residing in any known location, be it Ultimoria or elsewhere, and is simply hiding in a location that only Invictus himself is capable of accessing.

Design Notes
Originally there was no intention for Invictus to even exist. However, upon noticing a recurring trend with each installment to the Ultimorian stories and noticing a bad case of Serial Escalation and Sequel Escalation, it was ultimately decided that Invictus would be designed solely to showcase the absolute maximum in godhood abilities an Ultimorian Universe Character would ever achieve. In other words, he is effectively designed as a Level Cap in which no other Ultimorian designed after him is allowed to surpass. Not only that, but if said characters get stronger than their normal strongest abilities, his own abilities always scale to be vastly higher in comparison; in other words, he is more powerful than all of his creations combined.

Invictus is also designed as a the Deus Ex Machina trope manifested into physical form; this also explains his vast size when compared to the Primordial Deities, and what his ultimate role in the end of the NUC Era has him doing; in a fight he would've otherwise lost, he physically denies the possibility of losing against a villain because his condition and power resets back to full strength upon having it all dropped to 0; he is literally impossible to even remotely defeat or even kill, and this is the exact reason why he was never intended to exist in the first place until the climax of the NUC Era came into question. He's also the reason why Ancient Oblivion failed to do anything permanent as well; because he denied that from actually being the case.