John Petrov Plamenatz (May 16, 1912 in Cetinje, Montenegro – February 19, 1975 in Hook Norton, England) was a political philosopher, who spent most of his academic life at the University of Oxford. Born to an upper-class Jewish family that had to flee Montenegro after the German and Austro-Hungarian occupation in 1916, he came to England as a boy and was raised there. His father Peter had been Foreign Minister for Montenegro, and his mother was of aristocratic background. Peter Plamenatz was forced to leave Montenegro in 1917, and John was sent to England.
He was educated at Clayesmore School, whose head master and founder, Alexander Devine, was an activist for the Montenegrin cause, and at Oriel College, Oxford, where he read history. Plamenatz's speciality was political theory, which he spent most of his academic life teaching at the University of Oxford. When WWII broke out, he joined an anti-aircraft battery, and he was naturalized in 1941. At the end of the war, he returned to All Souls, and he spent the rest of his life at Oxford. From 1951 to 1967 he was a research fellow at Nuffield College, before returning to All Souls as Chichele Professor. He was a Fellow of All Souls College, 1936–51, and from 1951 to 1967 a Fellow of Nuffield College. He returned to All Souls as a professorial Fellow in 1967 when he succeeded Isaiah Berlin as Chichele Professor of Social and Political Theory.