Quoggoth is Great Old One in the expanded Cthulhu Mythos. He was created by Marvel Comics, first appearing in the #12 issue of Wolverine: First Class in 2009. His background is influenced by elements of Cthulhu's story.
Quoggoth is one of the Old Ones, created by Shuma-Gorath himself. Who served his creator for aeons, until 100s of millions of years later, he perceived himself to be more powerful than his lord and rebelled against Shuma-Gorath. Although he was unable to destroy his rebellious disciple, Shuma-Gorath imprisoned him within a sunken sepulchre.
Millions of years later, the island upon which the sepulchre was located was brought up to the ocean's surface and used by Magneto as his base, until his defeat at the hands of the X-Men. When they found themselves stranded on the island, Quoggoth brought Cyclops and Shadowcat to the sepulchre. He attempted to make a deal with Shadowcat to get them to release him from his prison but failed to convince Cyclops. They fled and tried to escape, battling the pursuing spawn generated by Quoggoth. Neither Cyclop's optical blasts nor Shadowcat's phasing powers were able to get through the doors that were covered by mystic sigils. Wolverine heard their screams from the other side of the door, and freed them with his claws by prying off the crystal seal. Quoggoth attempted to follow after them but Cyclops managed to close the doors in time with his optic beams as Wolverine put the crytsal seal back in place, thereby once again sealing Quoggoth.
Not even a telepath of Xavier's power was able to sense him, despite being on the same island. Quoggoth was able to produce spawn from its form, which varied from winged bat-like creatures to one that looked like a little human girl. It's touch was able to shock and stun Shadowcat and it could elongate its tentacles to great lengths. Blasts from Cyclops were unable to wound, much less destroy its tentacles. Considering the fact that Shuma-Gorath's power is such that it's aura-pressure alone could destroy multiple galaxies and it could even destroy a universe with it's most powerful blast, and yet could not destroy Quoggoth only imprison it, Quoggoth must be a cosmic and perhaps even a multiversal threat.