This one’s not actually mine, so instead of just copying it wholesale, I’ll link it for you:
It’s a CR 9 large humanoid, something like a cross between an ogre and a mind flayer. Not as huge and epic as a star-spawn of Cthulhu, but definitely an “Oh #&^%@!!!” moment for most parties. Makes a great solo/final boss for a level 7-8 adventure with a Lovecraftian/Howardian vibe.
It’s currently written with psi-like abilities (c/o Psionics Unleashed, which is thought of by many as the “core” psionic rules for Pathfinder, even if it’s from a third party). The ability descriptions are in the d20PFSrd, but if you don’t want to use those, they could easily be swapped out for similar spell-like abilities instead.
Created by Tim Wallace. Nice job, Tim!
PS: Yes, I know it’s not really Monday. ;P