Sir George Walter Prothero was born on October 14, 1848, in Charlton, Wiltshire, England.

He was a British historian, writer, and educator. He was educated at Eton, King's College, Cambridge (1868-1872), and the University of Bonn (1873-1874). He was elected a Fellow of King's College and became its history lecturer in 1876. In 1894, he became the first Professor of Modern History at the University of Edinburgh. In 1899, he accepted the editorship of the Quarterly Review in London, a position he held until his death. Prothero was elected President of the Royal Historical Society (1901–1905), Fellow of the British Academy (1903), Rede lecturer at Cambridge (1903), Lowell lecturer at Boston University, Schouler lecturer at Johns Hopkins University, USA (1910), and Chichele lecturer at Oxford (1915, 1920). He was co-editor of the Cambridge Modern History (1901–1912) and general editor of the Cambridge Historical Series. Prothero acted as a historical adviser to the Foreign Office between 1917 and 1919. In 1920, he was knighted for his services to the peace effort.

In 1882, he married Mary Frances Butcher (1854–1934). He died on July 10, 1922, in London, England.