[Cult] Cthulhu will devour everyone!

and they don't really look alike at all, except for 2 arms, 2 legs, and a head...
no multi-segmented face.
if Flayed Ones resemble anyone, it's probably Arnold Schwarzenegger at the end of each of the Terminator movies - pieces of meat on a metallic skeleton.
...and it's definitely not the "strongest weapon"; they'll be shot down by heavy bolters before they even get close, and digging won't help - marinated in rhino, they're gone, and they pop up again. on the contrary, it's one of the weakest and most unreliable things.

there really was such a mythical creature

funny tautology, Siever, don't you think?:)

P.S. I suggest that we don't reject/exclude all cultists and sectarians from the league of gentlemen. otherwise, it's nonsense. we fight Cthulhu and burn him out completely, and they spread their seeds of heresy in our ranks...