Which author formed the Inklings literary group with C.S. Lewis at Oxford?

J.R.R. Tolkien formed the Inklings literary group with C.S. Lewis at Oxford. The Inklings were an informal discussion and writing circle rather than an official society with a fixed membership list. They met mainly at Oxford venues during the 1930s and 1940s, including a pub known as The Eagle and Child, often nicknamed “The Bird and Baby.”

Tolkien and Lewis became close friends after meeting in Oxford and shared an enthusiasm for myth, language, and imaginative literature. Tolkien read portions of The Lord of the Rings to Lewis, while Lewis supported Tolkien’s work and discussed his own fiction with the group. Other important Inklings included Charles Williams and Owen Barfield.

Charles Williams was therefore also a notable Inkling, but he was not the answer to the question asking which author formed the group with Lewis. Dorothy L. Sayers was a contemporary writer and friend of Lewis, but she was not a member of the Inklings.