Abominations are large, pale creatures with black eyes. They appear to be a crossbreed or chimera of humans and Zetans, with significantly more humanlike physiques than Zetans. However, they seem to be unable to talk and are uniformly brutish and hostile, to human and Zetan alike. After spotting a target, an abomination will point at it and wail loudly, and then attack with its long arms. When killed, their bodies contain various items such as alien power modules or alien epoxy. They can also be looted for packs of cigarettes, pre-War money, harmonicas or pre-War books.
Alien captive recorded log 19 mentions abominations, with the person recorded having learned that humans are used to make Abominations somehow, although he believes it involves turning humans into Abominations rather than trying to mix or crossbreed humans and Zetans.
↑Fallout 3 Official Game Guide Game of the Year Edition p. 728: "The true horror of the Aliens’ abduction begins to sink in as you discover the more grisly side of their probing. This series of chambers is dotted with the corpses of those of particular interest to these fiends, along with the Aliens’ greatest triumph: half-human, half-Alien hybrids known only (and suitably) as Abominations."
↑Fallout 3 Official Game Guide Game of the Year Edition p. 714: "Dear god, what abominations are these?! Oh right, that’s exactly what they are. These half-human hybrids can’t be reasoned with."