University College London (UCL) is a public research university located in London, United Kingdom, and the oldest and largest constituent college of the federal University of London. Founded in 1826, UCL was the first university institution to be founded in London and the first in England to be established on an entirely secular basis, to admit students regardless of their religion and to admit women on equal terms with men. UCL became one of the two founding colleges of the University of London in 1836.

UCL's main campus is located in the Bloomsbury area of central London, with a number of institutes and teaching hospitals located elsewhere in central London. UCL is organised into 10 constituent faculties, within which there are over 100 departments, institutes and research centres. UCL has around 26,220 students and 10,100 staff and had a total income of £869 million in 2011/12, of which £301 million was from research grants and contracts. UCL has around 4,000 academic and research staff and 650 professors, the highest number of any British university.

UCL is ranked 21st in the world (and 3rd in Europe) in the 2012 Academic Ranking of World Universities,[8] 4th in the world (and 2nd in Europe) in the 2012 QS World University Rankings and 17th in the world (and 5th in Europe) in the 2012-13 Times Higher Education World University Rankings. For the period 1999 to 2009 UCL was the 13th most-cited university in the world (and the most-cited in Europe). There are 26 Nobel Prize winners and three Fields Medalists amongst UCL’s alumni and current and former staff.

UCL is part of three of the 11 biomedical research centres established by the NHS in England and is a founding member of UCL Partners, the largest academic health science centre in Europe. UCL is a member of the Association of Commonwealth Universities, the European University Association, the G5, the League of European Research Universities, the Russell Group, UNICA and Universities UK. It forms part of the 'Golden Triangle' of British universities.