Eärendil the Mariner and his wife Elwing are characters in J. R. R. Tolkien's Middle-earth legendarium. They are depicted in The Silmarillion as Half-elven, the children of Men and Elves. He is a great seafarer who, on his brow, carried the Morning Star, a jewel called a Silmaril, across the sky. The jewel had been saved by Elwing from the destruction of the Havens of Sirion. The Morning Star and the Silmarils are elements of the symbolism of light, for divine creativity, continually splintered as history progresses. Tolkien took Eärendil's name from the Old English name Earendel, found in the poem Crist A, which hailed him as "brightest of angels"; this was the beginning of Tolkien's Middle-earth mythology. Elwing is the granddaughter of Lúthien and Beren, and is descended from Melian the Maia. Through their progeny, Eärendil and Elwing became the ancestors of the Númenorean, and later Dúnedain, royal bloodline.

Middle-earth is the setting of much of the English writer J. R. R. Tolkien's fantasy. The term is equivalent to the Miðgarðr of Norse mythology and Middangeard in Old English works, including Beowulf. Middle-earth is the human-inhabited world, that is, the central continent of the Earth, in Tolkien's imagined mythological past. Tolkien's most widely read works, The Hobbit and The Lord of the Rings, are set entirely in Middle-earth. "Middle-earth" has also become a short-hand term for Tolkien's legendarium, his large body of fantasy writings, and for the entirety of his fictional world.