In the fiction of J. R. R. Tolkien, Nan Elmoth was the forest in Beleriand east of Doriath and southeast of the River Celon. In Tolkien's legendarium it is the archetype for all the other enchanted forests such as the Old Forest, Mirkwood, Lothlórien and Fangorn.
Melian and Thingol courted one another in Nan Elmoth before they founded the realm of Doriath. It was an enchanted wood at the east end of the east-west valley that ran between the northern edge of the forests of Doriath and the mountains of Ered Gorgoroth. During the time Thingol and Melian were there the trees grew to be the tallest and darkest in Beleriand, blocking the sun entirely from the forest floor. Eöl the Dark Elf and famed elven smith dwelt there. Nan Elmoth was held to be part of Doriath, therefore Eöl paid Thingol with the sentient, magic, black sword Anglachel as a fee for keeping it as his fief and holding it free of the enemy. Eöl had, for most of the First Age, a nearly exclusive trade agreement with the Dwarves of East Beleriand. Eöl kept his dwelling and smithy in the midst of the wood near the pool of Gladuial. In a darker echo of Melian's enchantment of Thingol, Eöl also enchants Aredhel when she enters the wood. This enchantment is described as an ensnarement. Eöl and Aredhel have a son, Maeglin, who is much involved in the tales of great city of Gondolin.