What academic subject did Tolkien teach at Oxford’s Pembroke College?

At Oxford’s Pembroke College, J.R.R. Tolkien taught Anglo-Saxon.

Tolkien became Rawlinson and Bosworth Professor of Anglo-Saxon at Oxford in 1925, a position he held until 1945. Anglo-Saxon is the traditional name for Old English, the language used in early English literature such as Beowulf. His scholarship in this field made him one of the important twentieth-century academic specialists in early English language and literature.

He later moved to Merton College, where he became Merton Professor of English Language and Literature. His teaching and research were closely connected to his fiction: he understood languages as historical systems and built fictional languages with their own sounds, grammar, vocabulary, and development.

A common misunderstanding is that Tolkien was primarily a professor of mythology. Myth and legend were central to his creative work, but his Oxford appointments were formally in language and literature, especially Old English and related fields.