Abomination

 are the result of alien experiments on abducted humans. They are found on the board of Mothership Zeta.

Biology
Abominations appear to be a hybrid of a human and an alien, and they are hostile to anything that is not one of them, including aliens. When they are shot, they bleed red blood, like humans and most other Earthen creatures, but when they lose their limbs, they bleed green blood, like aliens. They also emit "growls" that are similar to a Feral Ghoul's, further suggesting they're alien/human hybrids.

Loot
When they are killed their body can contain normal alien items like Alien Power Modules or Alien Epoxy but sometimes human items can be found like Pre-war Money, Harmonicas, Human Flesh, and Pre-War Books.

Appearances
Abominations appear in the Mothership Zeta add-on for Fallout 3.