John Petrov Plamenatz (May 16, 1912, Cetinje, Montenegro – February 19, 1975, Hook Norton, England) was a political philosopher, who spent most of his academic life at the University of Oxford. He was born in Montenegro, but came to England as a boy and was raised there.
Plamenatz was the son of Peter Plamenatz and Ljubica Matanowitch; he came to England in 1919. He was educated at Clayesmore School, whose head master and founder, Alexander Devine, was an activist for 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. 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.
He was a member of the government in exile of the Kingdom of Yugoslavia in London during the Second World War. During this period he wrote "The Case of General Mihailovic".
In 1943 he married Marjorie Hunter, one of his students; there were no children. He lived at All Souls and at Scotland Mount, Hook Norton, Banbury, Oxfordshire. His principal recreation was walking.
- Consent, Freedom and Political Obligation (1938)
- What is Communism? (1947) with Stephen King-Hall
- The English Utilitarians, with a reprint of Mill's Utilitarianism (1949) and later editions
- The Revolutionary Movement in France 1815 to 1871 (1952)
- From Marx to Stalin (1953)
- German Marxism and Russian Communism (1954)
- On Alien Rule and Self-Government (1960)
- Man & Society. A Critical Examination of Some Important Social & Political Theories from Machiavelli to Marx (2 vols, 1963) and later editions
- Readings from Liberal Writers, English and French (1965) editor
- Leviathan, edited & abridged by John Plamenatz. Thomas Hobbes (Author). Publisher: London: Fontana (1969)
- Ideology (1970)
- Democracy and Illusion: An Examination of Certain Aspects of Modern Democratic Theory (1973)
- Karl Marx's Philosophy of Man (1975)
- Machiavelli, Hobbes, and Rousseau (2012)
- "John Plamenatz". Oxford Biography Index of the Oxford Dictionary of National Biography, index number 101031552. Retrieved September 2, 2010.
- Isaiah Berlin, Plamenatz, John Petrov (1912–1975), Oxford Dictionary of National Biography, rev. first published Sept 2004; online edition, Oct 2008
- Lecture referencing Plamenatz from the BBC
- Who was Who, 1971-80, London : A. & C. Black, 1981
- * various (1985). 'The Nature of Political Theory'. ISBN 978-0198274735., a collection of essays by and about Plamenatz.