John Keiran Barry Moylan Nicholas (1919 - 2002) was a British professor of law. He began teaching at Brasenose College at Oxford University in 1946, and he was the principal of the college from 1978 to 1989. He gave up the position at the appointed age of 70, but he did not retire.
Nicholas' An Introduction to Roman Law is a standard text in the study of Roman law.
