Skeletoid

Skeletoids are extradimensional aliens that have been augmented with the ability to fly in 1997 game X-Com: Apocalypse.

Overview
Skeletoids are yellow hued humanoid aliens with intelligence on par with humans. These aliens stand around six and a half feet (two metres) tall. They have a distinct head, which is unusual for aliens from the other dimension. Skeletoids have deep sunken eyes and a rectangular mouth with which it feeds itself. Olfactory organs are not present, although various openings in the head may serve this purpose.

They have shoulders, knees and elbows - all of which are often missing from other aliens. Their body is surprisingly light even with skeletal support. Hands are poorly equipped to manipulate human objects - they lack fingers and most of their so called palms house a large, orb-like growth. Same kind of implants are found inside of their body, and seem to be the source of their capability to fly.

Legs appear malformed, but this is not because of any kind of atrophy. Even if skeletoids are able to fly, they can walk just fine, too.

Role in invasion
Skeletoids are encountered along with Anthropods in alien military operations. They are intelligent and capable of taking coordinated action. Where anthropods are a typical mass produced rank-and-file soldier for the aliens, skeletoids are highly specialized shock troopers. Their construction is likely more complex than those of anthropods, and it is unknown if the flight implants must be attached in the alien dimension or not. However the case, skeletoids are not encountered until alien invasion in Mega-Primus escalates and aliens start using more oppressive control methods.