According to Brian Lumley's Titus Crow saga, one of the three sons of Cthulhu. One of the more pronounceable of the three, he lacks the tongue-twisting challenge of his siblings, and therefore sounds less impressive. Only fall back on invoking Zoth-Ommog if very, very drunk, incapable of pronouncing Yog-Sothoth, or American.
If you must go looking, he's Dwelling in the Deep (why does this sound so familiar? Is there some circular that goes around all Cthulhu Mythos writers that never gets as far as me?), off the island that Lumley terms Ponape - now called Pohnpei.