Having just finished Origin Saga...or at least the raw, I would like to comment about the main antagonist, Doctor Psychi. In short...he's probably the most well developed Alien Invader, and general main antagonist, as for as the main series is concerned. ) Also, warning for the end of Origin Saga
Firstly, let's look at his goals, no, it's not invade Earth, or even any other planet, in fact, you could say he is the response to the cliche of alien invaders in the Ultra series.Psychi's goal is an end to conflict, an end to war in general, he just goes about it in questionable ways.
The best way I can describe Psychi is not a villain, or even a mad man, though he does seem to present himself as such. No the best way I would describe him... is desperate. Psychi is desperate to end war, after having lost his parents in a war. In a way, Psychi never 'grew up' out of that little boy, he just 'got older'. Psychi is actually, perhaps, the most sympathetic of antagonists in the series, as his actions come out of a place of sorrow, not greed, agression, arrogance, bigotry or other negative and petty emotions that seem to motivate other alien villains.
At the end of the day, Psychi, just isn't really a villain, heck his robot risked its life to save people who were practically his master's enemies, no 'villain' would program that. Also, given the flashback of the series, and the actions of Queen Bezelb, I would go so far and say 'she' is the true villian, using Psychi and through him, everyone to get what she wanted.
Here's a disturbing thought...we didn't see who it was the Wraith Aliens were fighting, we just know his parents died as collateral damage from the war, if the visuals is anything to go by... Then we see that he met Queen Bezelb when he was a child...what if the force his people were fighting, were each other, or even other species, but a war against a Bezleb infestation... Now that is tragic...