History
Gathonagog was an archaic god and a demon residing in the depths of a black dimension, a realm of chaos and madness, in the void beyond the stars where the Ancient Ones slumber.[1] It isn't revealed if Gathonagog is himself one of the Ancient Ones.
Gathonagog was summoned by Dr. Doom who took possession of the body of the Silver Surfer, previously taken prisoner by Dr. Doom, and under the command of Doom the demon in the body of the Surfer traveled to New York to attack Reed Richards, but he he didn't find it as Reed had left with Sue and Johnny for a science convention, instead he found the Thing who was fighting with Spider-Man over possession of the cannoli. Understanding the situation, Spider-Man asked the Thing to distract the demon, while in the meantime he used a device from Reed and to expel the demon from the body of the Surfer.[1]Notes
- Given the description of Gathonagog's background, and him being called "Cthulu" by the Thing, Gathonagog is seemingly a nod to the Cthulhu Mythos.