I kinda liked the ADVENT guys as mostly-human thugs of the Hybrid org. Not as their own thing as in nuCOM, but kinda like a Hybrid version of the Floater.
This sort of gels with UFO lore, too, having outright aliens, hybrids who can't really bear close scrutiny, and then some guys who are a just bit off. Tend to wear sunglasses and face cover, belong to shady pseudo-governmental organisations, stomp on journalists who are too nosy, get sacrificed when the chips are down.
I know that Solarius is moving away from classic alien lore, though.