Starspawn

Starspawn, also known as Cthulhi or Xothians, are a highly intelligent species from another part of the universe, and many of their abilities derive from the differing fundamental natural laws from whence they come. They have a physical similarity to The Great Cthulhu and they can change their proportional size and symmetry at will. For instance, a starspawn could push most of its mass into its wings to give it the needed size to fly or cause a single tentacle to grow to supreme length- as its body collapses in behind it - to reach a victim at a great distance. As needed, it could also sprout a sensory organ at the end of th tentacle or reach around a target to attack from more than one direction.
In their standard state, starspawn have four limbs and two wings, as well as a face dominated by a mass of feelers. They can alter the proportions of this shape as they please but always adhere to the same basic structure.
Starspawn do not have brains as humans understand them - instead, every part of their body is a sort of nerve or brain cell. Thus, the larger a starspawn, the more intelligent, because its sheer volume increases its intelligence and abilities. Their minds are wholly alien, full of psionic and magic potential. Great Cthulhu is, technically, just another starspawn, but his enormous size reflects the fact that he is also among the oldest and most powerful.

Ecology

Starspawn reproduce by budding or fission: a smaller larval starspawn simply drops off a large one. The smaller entity retains a good portion of the parent's wisdom and knowledge, but has fewer or weaker spells and psionics available, as its lesser-size means it h as a more limited mental capacity.
In any case, even the smallest larval starspawn possesses a genius-level intellect by Human standards, though this is difficult to measure due to the alien nature of their minds. They typically exist on different plans of existence simultaneously and obey different natural laws than those Common to humanity.
Starspawn are immortal and almost impossible to kill. When sealed away by magic or physical effects, they can sleep for centuries without difficulty.

Cthulhu in the Dark by Chad Watson via Midjourney