J.R.R. Tolkien’s academic specialty at Oxford before becoming a professor of English literature was Anglo-Saxon.
Tolkien became a professor of Anglo-Saxon at Oxford in 1925. The subject, now often called Old English studies, involved the language and literature of Anglo-Saxon England. His expertise included texts such as Beowulf, which profoundly influenced his scholarly work and his approach to invented languages and mythology.
In 1945, Tolkien moved to the Merton Professorship of English Language and Literature at Oxford. This later position broadened his formal academic title, but his earlier appointment as professor of Anglo-Saxon is a key part of his career.
The term Anglo-Saxon here refers to the language and culture of early medieval England, not to Tolkien’s fictional peoples. Tolkien’s professional work in historical linguistics helped shape the depth of names, alphabets, and languages in The Hobbit and The Lord of the Rings.