Xothian

The Xothians (aka, as the Star Spawn of Cthulhu) are a race of Eldritch beings that look like Cthulhu that serve the Great Old One, though it is unknown as to whether they are his offspring, his creations, or a race from which he came from.

Biology
The Xothians have a malleable body with some degree of shapeshifting, such as extending their arms or tentacles. The basic form though does not change which is that of a somewhat corpulent green body, clawed hands and feet, small leather wings, and a tentacled mouth.


 * Lovecraft = The sizes given by various authors in the Cthulhu Mythos has varied greatly. Described with words such as "huge" or "mountainous".
 * Pathfinder (Paizo Publishing) = The smallest of the Star-Spawn are 30 ft tall, and heights can reach as high has 50ft tall. Xothians have psionic abilities and can use magic. Space flight is an ability they possess but it takes them months to cross a solar system. When they want to get to a world faster, they open "gates" to those worlds.
 * Eldritch Skies (Battlefield Press) = The Cthulhoids (and Cthulhu) are transcendental beings who exist in hyperspace and are able to move across the planes within hyperspace, and manifest themselves in the material universe. When they appear in the material universe, how they appear is theorized to be a function of our minds imagining how they should appear. In the case of humans, our minds see a corpulent humanoid form with leather wings, claws, and a tentacled face. Cthulhoids have psionic abilities and feed on the psychic energies of sentient life forms. Before being imprisoned in hyperspace, they were able to manifest physically anywhere in the cosmos for long periods of time.

Agenda

 * Pathfinder = The Star Spawn have one goal only, to bring about the End Times. In service of that goal, they indirectly influence individuals or populations, or directly control cults to bring about the apocalypse in their respective worlds. The only reward for those who serve them is to be the last to die. They don't hate those they kill or cause to die, they are simply an obstacle to the great plan that must be removed. Which is to the end of the universe itself.
 * Eldritch Skies = The Cthulhoids are doing all they can to break out of the hyperspace prison created by the Elder Weapon that designed by the Yithians and Elder Ones, hundreds of millions years ago on Earth. The prison is supposed to last a billion years and they are only one fourth of the way through. A few dozen were not trapped in the prison, but they stay away from the Solar System. Cults are attempting to weaken the hyperspace prison so they can break out. In the meantime they can only physically manifest within a couple 100 miles from R'lyeh for a few minutes every 1000 years due to shifts in the streams of hyperspace. If and one they break out, they will return to feeding on the psychic energies of the sentient worlds of the universe.


 * Xothic Wars (Gobbotown Games) = In 250 million BC, the Xothians are invading Earth from another dimension. They aim to establish a power base in this universe for Cthulhu (who is from that other dimension). His ambitions in his home dimension to become a greater diety / entity have been blocked / prevented by the higher beings. They plan to turn Earth into a place where he will complete a ritual that will have him ascend to greater godhood. Standing in the way are the Qhrell (Elder Things) and therefore there is a great war raging in prehistoric Earth.


 * The Cruel Empire of Tsan Chan (Chaosium) = In 5000 AD, the Xothians are serving as the generals, champions, and super weapons of the Dreamers (an army of humans and mutates, turned insane by the awakening of Cthulhu and led by the Deep Ones). They wage war against the Cthonians in Africa and the human-controlled Empire of Tsan Chan (formerly China) who have their own Great Old One-like creations, are supported by the Serpent People (subterranean civilization) and supplied the Elder Things (galactic power). In between battles, the Xothians will stand still and either meditate or worship the Great Old Ones which has enabled the humans to recover from defeats or take advantage of victories.