Through my playthroughs I have sometimes found a glimpse, a snapshot of a race, of an individual xeno, that doesn't seem to fit any minor nor major races. I've made an effort, well, not so much, as it usually just needed to press printscreen, to catalogue some of these. In time probably more snaphots would arrive. If individuals would be clasified prositively as e.g random weird mutated Haroshem  -  I would delete said picture. 5 images per post, for clarity. I would possibly migrate them to an outside source, but I don't have any repository.

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I believe all that is nothing more then generic alein species/filler for the art.

Same as @sublustris. There's a lot of generic art in Endless series, like lots of humans in EL art, while in EL are lots of non-human factions (IIRC in an EL thread Amp told that it was generic art).