Y'Golonac is a Great Old One. He is the god of perversion and depravity – not just "average" human perversions or depravities, but any that can be conceived of by a sapient being (sane or otherwise).
He has not made an appearances in the actual game, only appearing as a Steam card for Alone in the Dark: Illumination.
Appearance[]
His appearance resembles the Goblin creature in stature and design.