Chimera Sui Generis (Classic)

Appearance
Chimera Sui Generis are a green humanoid species with long tentacles on their head or chin like those of an octopus or squid. The number of tentacles can vary. They have four pointy fingers and two toes. Most female Chimera Sui Generis have tendrils on their head, while males have them on their chin or all around their head to resemble hair or beards, respectively.

Original Series and Omniverse
Their bodies, if not cybernetically altered, have red circuit/vein-like patterns. Their tentacles have spots in a mud-like pattern, being yellow or dark green. They have red eyes. Their heads supported a green neck-pillow-shaped sac in the original series that connected both of their cheeks from the back of their heads. This was only seen in Vilgax in Omniverse. Their lips are black and have lines connecting to their sac. Again, only Vilgax had this feature in Omniverse as Myaxx has shown to have more feminine lips.

Alien Force and Ultimate Alien
The red circuit/vein-like patterns do not appear in these shows. Rather, the Chimera Sui Generis have a smooth torso and wrinkled limbs. Also, all Chimera Sui Generis have minty green eyes, with the exception of Myaxx and Vilgax. When in their 'true form', they are more cephalopod-like than humanoid in appearance. Their heads become massive in size and support several black horn-shaped spikes running down their heads. There are pink cracks above their sharper eyes. The bottom of their bodies are pink with line patterns and have a triangular mouth. Unlike cephalopods found on Earth, their mouth appears on their face, sporting eight sharp teeth, five on top, three on the jaw, and three extra each shown on the four tentacles closest to their mouth, while having about 20 tentacles in total. There are also gill-like growths underneath the eyes. Their skin is more wrinkled compared to their humanoid form.

Diet
Chimera Sui Generis have at least shown to be able to consume meat and crustaceans.

Powers and Abilities
Chimera Sui Generis have incredible natural strength.

Chimera Sui Generis have incredible durability. Even before being enhanced, Vilgax survived a nuclear explosion at point blank range, though he was widely believed to be dead after this.

Chimera Sui Generis have incredible agility.

Chimera Sui Generis have the ability to transform into a large squid-like form and back at will, but can't if they're too weak.

Weaknesses
When in their 'true form', they cannot switch back if they are too weak. They are also highly immobile on land in that form and require water in order to breathe, despite their normal ability of space survivability.

Despite their enhanced durability, there is a limit to how much damage their bodies can take before being fatally injured.

Notable Chimera Sui Generis

 * Vilgax
 * Vilgax (Future)
 * Vilgax (Gwen 10)
 * Myaxx
 * Citizens of Vilgaxia
 * Unknown (the Omnitrix's DNA sample of a Chimera Sui Generis)

Etymology
The name Chimera Sui Generis comes from "Chimera", a mythical beast with parts from many different animals, and "Sui Generis", a Latin term that means "of its own kind/genus" or unique in its characteristics which roughly translates to "Chimera of its own kind".

Trivia

 * Milleous once referred to the Chimera Sui Generis as "Vilgaxians".
 * The Chimera Sui Generis look like Cthulhu, a literary evil deity and conqueror (like Vilgax) created by author H.P. Lovecraft.