What was the name of the Oxford college where J.R.R. Tolkien taught from 1925?

J.R.R. Tolkien taught at Pembroke College, Oxford, from 1925.

Tolkien was appointed Rawlinson and Bosworth Professor of Anglo-Saxon at Oxford in 1925 and held the position until 1945. His college was Pembroke College, where he taught Old English and related subjects. During this period he wrote much of The Hobbit and began developing material that would later contribute to The Lord of the Rings.

In 1945 Tolkien moved to Merton College after becoming Merton Professor of English Language and Literature. That change is why biographies sometimes mention Merton in connection with his Oxford career. Pembroke College, however, is the correct answer for the first major Oxford professorship beginning in 1925.