Somerville College is a constituent college of the University of Oxford in England. It was founded in 1879 as Somerville Hall, one of its first two women's colleges. It began admitting men in 1994. The college's liberal tone derives from its founding by social liberals, as Oxford's first non-denominational college for women, unlike the Anglican Lady Margaret Hall, the other to open that year. In 1964, it was among the first to cease locking up at night to stop students staying out late. No gowns are worn at formal halls.

In 2021 it was recognised as a sanctuary campus by City of Sanctuary UK. It is one of three colleges to offer undergraduates on-site lodging throughout their course. It stands near the Science Area, University Parks, Oxford University Press, Jericho, and Green Templeton, St Anne's, Keble and St Benet's. Over a third of its 650 students are not from the UK. Over half the UK admissions are from state schools – close to the university average. Its total net assets in 2021 were £238 million, the seventh highest of an Oxford undergraduate college. Its sister college at Cambridge is Girton.

Among its alumnae have been Margaret Thatcher, Indira Gandhi, Dorothy Hodgkin, Iris Murdoch, Philippa Foot, Vera Brittain and Dorothy L. Sayers.

In June 1878, the Association for the Higher Education of Women was formed, aiming for the eventual creation of a college for women in Oxford. Some of the more prominent members of the association were George Granville Bradley, Master of University College, T. H. Green, a prominent liberal philosopher and Fellow of Balliol College, and Edward Stuart Talbot, Warden of Keble College. Talbot insisted on a specifically Anglican institution, which was unacceptable to most of the other members. The two parties eventually split, and Talbot's group (the "Christ Church camp") founded Lady Margaret Hall, which opened its doors for students in 1879, the same year as Somerville did.

Thus, in 1879, a second committee was formed to create a college "in which no distinction will be made between students on the ground of their belonging to different religious denominations." This committee was called the "Balliol camp" and had close ties to the Liberal Party. This second committee included A. H. D. Acland, Thomas Hill Green, George William Kitchin, James Legge, Henry Nettleship, Walter Pater, Henry Francis Pelham, its chairman John Percival, Grace Prestwich, Eleanor Smith, A. G. Vernon Harcourt, and Mary Ward. Other people who assisted in the founding were Anna Swanwick, Bertha Johnson, Charlotte Byron Green, and Owen Roberts.

This new effort resulted in the founding of Somerville Hall, named after the then recently deceased Scottish mathematician and renowned scientific writer Mary Somerville. It was felt that the name would reflect the virtues of liberalism and academic success which the college wished to embody. She was admired by the founders of the college as a scholar, as well as for her religious and political views, including her conviction that women should have equality in terms of suffrage and access to education.

Madeleine Shaw-Lefevre was chosen as the first principal because, though not a well-known academic at the time, her background was felt to reflect the college's political stance. Because of its status as both women's college and non-denominational institution, Somerville was widely regarded within Oxford as "an eccentric and somewhat alarming institution."

When it opened, Somerville Hall had twelve students, ranging in age between 17 and 36. The first 21 students from Somerville and Lady Margaret Hall attended lectures in rooms above a baker's shop on Little Clarendon Street. Just two of the original 12 students admitted in 1879 remained in Oxford for three years, the period of residence required for male students to complete a bachelor's degree.