Geoffrey Ernest Maurice de Ste. Croix (February 10, 1910 – February 5, 2000) was a British historian who specialized in examining the classical era from a historical materialist perspective.

De Ste. Croix was born in Macau and was educated at Clifton College, in Bristol. He left school at the age of 15 and become an articled clerk, which allowed him to train as a solicitor, without a degree in law. In 1926-40, De Ste. Croix practised as a solicitor.

He had a strong physique and was a talented tennis player, who once defeated Fred Perry. De Ste. Croix competed at Wimbledon in 1929.

During the Second World War he joined the Royal Air Force, and was stationed for a time in Egypt, where he had the opportunity to expand his knowledge of ancient languages. After the war ended, de Ste. Croix studied ancient history at University College, London. In 1950-53 he taught at the London School of Economics and Birkbeck College, before being appointed a fellow of New College, Oxford. He lived at Oxford for the rest of his life.

Within the circles of classical scholarship, de Ste. Croix — as an exponent of a Marxian epistemological approach — was frequently involved in debate with Sir Moses Finley, an advocate of Weberian societal analysis. The two often exchanged letters and their disagreements were always civil.

The two books for which de Ste. Croix is best known are The Origins of the Peloponnesian War (1972) and The Class Struggle in the Ancient Greek World from the Archaic Age to the Arab Conquests (1982). He was also a noted contributor on the issue of Christian persecution between the reigns of the Roman Emperors Trajan and Diocletian. Of particular note in this regard are the articles written by de Ste. Croix and A. N. Sherwin-White, each challenging the opinions of the other. There were four in total, displaying just the sort of light-hearted banter evident also in de Ste. Croix's correspondence with Moses Finley.

In this provocative and wide-ranging examination of the causes of the Peloponnesian war, first published in 1972, Geoffrey de Ste Croix argued against most previous historiography (which tended to blame Athens), that the Spartans and their allies must bear the immediate and ultimate responsibility for the war. The book includes a strong argument for the fundamental credibility of Thucydides' narrative, background on Corcyraean and Potidaean affairs, a lengthy re-examination of the Athenian decree excluding Megarians from the civic centre of Athens and the ports of the empire, and three chapters on Spartan and Corinthian foreign policy and relations with Athens from earliest times till the outbreak of was in 431 BC. Forty-seven appendices treat questions of detail.