Henry Jackson OM FBA (12 March 1839 – 25 September 1921), was an English classicist. He served as the vice-master of Trinity College, Cambridge from 1914 to 1919, praelector in ancient philosophy from 1875 to 1906 and Regius Professor of Greek (Cambridge) at the University of Cambridge from 1906 to 1921. He was elected a Fellow of the British Academy in 1903. He was awarded the Order of Merit on 26 June 1908. From 1882 to 1892 he sat on the Council of the Senate of the University of Cambridge, and was an active member of a number of the university boards. He lived within the walls of Trinity College for over 50 years. Born in Sheffield, he lived mainly in Cambridge, but died in Bournemouth.
Born on 12 March 1839 in Sheffield, the son of an eminent Sheffield surgeon of the same name and his wife, Frances, third daughter of James Swettenham, of Wood End, near Winksworth. He attended Sheffield Collegiate School and Cheltenham College before entering Trinity College Cambridge in 1858; he graduated BA in 1862 as third Classic. He joined the Cambridge Apostles in 1863. He became a fellow at Trinity College in 1864, and became Assistant Tutor in 1866, Praelector in Ancient Philosophy in 1875 and Vice-Master in 1914. In 1875 he married Margaret, daughter of the Reverend Francis Vansittart Thornton, vicar of South-Hill with Callington, Cornwall. They had two sons and three daughters.
Jackson's married life was clouded by the illness of his wife, for many years bedridden and unable to live at Cambridge; his wife spent time in a nursing home.
Together with Henry Sidgwick and others he essentially established the Cambridge university's supervisory system by introducing it in the classical side at Trinity. Other disciplines and other colleges soon followed suit. He was interested in university reform including the reform of Triposes (including the Classical Triposes), the admission of women for university education, the abolition of tests, and for the general reform of university and college statutes, and voted for women's degrees. He became Regius professor of Greek at Cambridge University, a post he was appointed to in 1906, following Sir Richard Jebb; after 1879 he became one of the editors of The Journal of Philology until his death. In July 1919, Jackson was honoured on the occasion of his eightieth birthday and his retirement as Vice-Master of Trinity College, with an address presented by the Master and Fellows.