The University of London is a collegiate research university located in London, England, consisting of 18 constituent colleges, nine research institutes and a number of central bodies.

The university is the second largest university by number of full-time students in the United Kingdom, with 161,270 campus-based students and over 50,000 distance learning students in the University of London International Programmes. The university was established by royal charter in 1836, as a degree-awarding examination board for students holding certificates from University College London and King's College London and "other such other Institutions, corporate or unincorporated, as shall be established for the purpose of Education, whether within the Metropolis or elsewhere within our United Kingdom". The university moved to a federal structure in 1900.

For most practical purposes, ranging from admissions to funding, the constituent colleges operate on an independent basis, with some recently obtaining the power to award their own degrees whilst remaining in the federal university. The ten largest colleges of the university are UCL, King's College London, Queen Mary, City, Birkbeck, the London School of Economics and Political Science, Royal Holloway, Goldsmiths, SOAS, and St George's. The specialist colleges of the university include the London Business School, the Royal Veterinary College and Heythrop College, specialising in philosophy and theology. Imperial College London was formerly a member before leaving the university in 2007. City is the most recent constituent college, having joined on 1 September 2016.

Many notable individuals have passed through the university, either as staff or students, including at least four monarchs, 52 presidents or prime ministers, 74 Nobel laureates, six Grammy winners, two Oscar winners and three Olympic gold medalists.

In post-nominals, the University of London is commonly abbreviated as Lond. or, more rarely, Londin., from the Latin Universitas Londiniensis, after its degree abbreviations.