Gorgumoth was the hound of the Vala Mandos who guarded Melkor in the Castle of Lumbi after he was overthrown by Tulkas.
Gorgumoth and the Castle of Lumbi are not mentioned in The Silmarillion. The event in the books stays the same wherein Melkor was chained by Angainor and cast behind the Door of Night.
- ↑ The History of Middle-earth, Vol. 2: The Book of Lost Tales Part Two, VI: "The History of Eriol or Ælfwine and the End of the Tales"