From 1925 to 1945, J.R.R. Tolkien taught Anglo-Saxon at Oxford University. His formal post was Rawlinson and Bosworth Professor of Anglo-Saxon at Pembroke College, Oxford.
Anglo-Saxon is the traditional name for Old English, the language used in England before and shortly after the Norman Conquest. Tolkien’s expertise included Old English literature, language history, and medieval texts.
His academic work strongly influenced his fiction. The sounds, structures, and histories of older languages helped him create languages and names for his invented peoples and places. His 1936 lecture Beowulf: The Monsters and the Critics also helped reshape scholarly discussion of the poem.
In 1945 Tolkien moved to Merton College and became Professor of English Language and Literature. Thus his Oxford career involved more than one professorship.