
Originally Posted by
MirronTulaxia
Given Exdeath and Kefka it wouldn't be impossible, but Ultimecia isn't an especially popular villain so I'm not too positive that would happen.
If Ultimecia shows up in the final wing of the Eden raid, it would not be like Exdeath, Kefka, and Chaos, but rather more like Xande and the Cloud of Darkness in Syrcus Tower and the World of Darkness: Original characters whose names and appearances are references to previous Final Fantasy characters. In Ultimecia's case, I would imagine she would turn out to be a former Warrior of Light from the Thirteenth, like Cyella and Unukalhai.
Or perhaps something considerably more convoluted, like the whole "Rinoa is Ultimecia" fan idea. For an example, here's some weird spitballing:
It could be Minfilia from the Exarch's Timeline, having survived the Eighth Umbral Calamity due to her Ascian-like existence. That would require an unreasonably lengthy explanation to work, I'd imagine, but it's not impossible.