C.S. Lewis was J.R.R. Tolkien’s close friend in the Inklings literary group.
The Inklings were an informal Oxford discussion and reading group whose members included writers and academics. Tolkien and Lewis met in the 1920s and developed a friendship strengthened by their shared interest in mythology, Christianity, language and imaginative literature. They often read works in progress aloud to one another.
Lewis’s encouragement helped Tolkien continue developing his fiction, while Tolkien influenced Lewis’s thinking about myth and literary tradition. Tolkien read parts of The Lord of the Rings to the group, and Lewis was among the early listeners who responded to the work as it evolved.
The friendship later became strained, especially after Lewis’s marriage and changes in their personal lives, but it remained a major relationship in Tolkien’s biography. Charles Williams and Owen Barfield were also associated with the Inklings, so they are plausible alternatives, but Lewis was Tolkien’s best-known literary friend from the group.