Ælfwine (called by the Elves Eriol) is a fictional character from J. R. R. Tolkien's Middle-earth. He was a medieval Englishman of c. AD 900. He appears in the early version of Tolkien's mythos and provides the framework for The Book of Lost Tales, as the first Man to find the Straight Road and visit Tol Eressëa after many millennia.

The name Ælfwine simply means "Elf-friend", and is the Old English equivalent of Elendil. The names Elvis and Alvin are modern descendants. It is possibly intended as a cognate of Albion.

Although there is no such framework in the published version of The Silmarillion, some of the later writings of Tolkien indicate that he didn't fully abandon the idea of a framework. However, although Ælfwine is still referred to in some post-Lord of the Rings writings, Tolkien ultimately changed the intended framework of The Silmarillion from the tale of Ælfwine to one based around Bilbo Baggins' edits of "Elvish lore".

Ælfwine is also given as the author of the various translations in Old English that appear in the History of Middle-earth series. A minor discrepancy is that whereas Ælfwine is described as hailing from the north-west of England, his Old English texts are in the Mercian dialect, which was Tolkien's favourite.