J.R.R. Tolkien introduced C.S. Lewis to the Icelandic saga tradition through their shared interest in medieval literature. Lewis and Tolkien were colleagues at Oxford and became close friends, although their relationship included serious intellectual disagreements.
Both men were members of the Inklings, a literary discussion group that met mainly at Oxford’s Eagle and Child pub and in Lewis’s college rooms. They read portions of works in progress to one another and discussed myth, language, literature, and Christianity.
Tolkien was a philologist and medievalist whose scholarship included Old English and Old Norse literature. Lewis’s own academic work focused on English literature of the Middle Ages and Renaissance, so their interests overlapped strongly.
Charles Williams and Owen Barfield were also important members of Lewis’s literary circle. However, Tolkien is the specific friend associated with broadening Lewis’s engagement with Icelandic saga material and northern mythology.