Geoffrey Stephen Kirk, DSC, FBA (//; 3 December 1921 – 10 March 2003) was an English classicist known for his writings on Ancient Greek literature and mythology. He was Regius Professor of Greek at the University of Cambridge from 1974 to 1984.
Kirk's time at Cambridge was interrupted by war. He joined the Royal Navy in 1941 and was commissioned as an officer one year later. He spent much of his service in the Aegean Sea with the Levant Schooner Flotilla commanded by Adrian C. C. Seligman. The unit included schooners and caïques engaged in irregular operations in support of Allied special forces. Kirk fought on many Greek islands and along a wide section of the Turkish coast. He was engaged in operations at Tekegas Barnu, Didyma, Icaria and Andros. He was awarded a Distinguished Service Cross (DSC) in 1945.
After the war, Kirk returned to Cambridge, graduated in 1946 and gained a research fellowship at Trinity Hall, Cambridge. He later became a lecturer and then a reader at Cambridge. He was elected a Fellow of the British Academy in 1959 and served as its vice-president in 1972–73. He also held visiting positions at Yale and Harvard. In 1974 he became the 35th Regius Professor of Greek at Cambridge.
Kirk had married Barbara Traill in 1950, and they had a daughter, Lydia. In 1975 he married Kirsten Ricks. He was supported by Lydia and four stepdaughters through ill health in his later life.
- Heraclitus, The Cosmic Fragments (1954)
- The Presocratic Philosophers: A Critical History with a Selection of Texts (1957) with J. E. Raven; a revised 2nd edition was published in 1983 with the help of Malcolm Schofield.
- The Songs of Homer (1962) later edited as Homer and the Epic (1965)
- The Language and Background of Homer: Some Recent Studies and Controversies (1964) editor
- Myth: Its Meaning and Functions in Ancient and Other Cultures (1970)
- The Nature of Greek Myths (1974)
- Homer and the Oral Tradition (1976)
- Archilochos (1977) with Michael Ayrton
- The Iliad: A Commentary (1985–93) six volumes, editor