Merlin's Ring is a fantasy novel by American writer H. Warner Munn, the third in a series of three based on Arthurian legend.

The novel is a continuation of the story in The Ship From Atlantis, telling of Prince Gwalchmai's star-crossed love for Princess Corenice of Atlantis in her various reincarnations, along with his centuries-delayed quest to secure aid and settlers to shore up the faltering empire established by his father and refugees from the fallen kingdom of Arthur in the New World.

The Britain he finally reaches is a prostrated land transformed into England by its Saxon conquerors, with his father's exile long forgotten and his countrymen incapable of undertaking any sort of colonization project.

He is abetted down through the centuries by the magical ring of his godfather Merlin, responsible for his longevity, and by Corenice.

Highlights include the hero's visit to Faerie, his service as a companion to Joan of Arc, and his final revelation in Iceland of the secret of the New World to a Genoan merchant, Christopher Columbus.