Star Spawn of Cthulhu
Primed and ready to paint.
Initially described as "a land race of beings shaped like octopi and probably corresponding to the fabulous pre-human spawn of Cthulhu," (HPL: "At the Mountains of Madness")
The Star-Spawn are also described as being "composed of matter more widely different" than that which is native to our universe. And their physicality so malleable that they might to some small degree be called shapeshifters, for "They were able to undergo transformations and reintegrations impossible for [The Elder Things]."
This aspect is even contrasted against the Elder Things descriptions as "strictly material" and native to "the known space-time continuum", implying an origin with perhaps vastly different governing laws of nature to limit the Star-Spawn.