The golden triangle is the triangle formed by the university cities of Cambridge, London, and Oxford in the south east of England in the United Kingdom. The triangle is occasionally referred to as the Loxbridge triangle, a portmanteau of London and Oxbridge or, when limited to five members, the G5.

The list of universities considered to be members of the golden triangle varies between sources, but typically comprises the University of Cambridge, the University of Oxford, Imperial College London, King's College London, the London School of Economics and University College London. Some sources omit either or both of King's College London and the London School of Economics; while occasionally other universities are included, e.g. the London Business School and the London School of Hygiene and Tropical Medicine, or all of the higher education institutions in the three cities.

The universities typically considered members of the golden triangle are amongst the longest established universities in England and possess some of the largest financial endowments across the United Kingdom. Total enrolments for the 2023/24 academic year range from about 12,900 at LSE to 51,400 at UCL, with UCL being the second-largest university in the United Kingdom by total enrolment.

Notes:
^† Only 2022/23 endowment figures available for Cambridge

With the exception of the LSE, the five other institutions typically considered members of the golden triangle have among the highest research incomes of all British universities, ranking in the top seven of British universities by research grant and contract income (along with Manchester and Edinburgh) and in the top six of English universities by Research England recurrent funding (along with Manchester). These five institutions all have significant fractions of their research grant and contract income from clinical medicine, varying (in 2021/22) from 41.7% (Cambridge) to 63.6% (King's College London), compared to an average across the UK of 34.4%. Overall, 50.9% of the 2020/21 research grant and contract income of the five institutions (50.0% if the LSE is included) came from clinical medicine research, and they accounted for 34.7% of all research grant and contract income of UK universities in 2020/21 (35.2% if the LSE is included). Each university receives millions of pounds in research fundings and other grants from the UK government, criticised by leaders of some other universities as disproportionate and not in the best interests of the country as a whole. In 2013/14, universities in Oxford, Cambridge and London received 46% of research funding in the UK, up from 42.6% a decade earlier.

Following the 2021 Research Excellence Framework (REF), the golden triangle universities saw a fall in their share of Quality Research funding (recurring funding based on the REF results rather than grants or other sources) from Research England. Analysis by Times Higher Education showed that the share of funding going to the golden triangle (not including the LSE in this analysis) fell from 35.36 per cent in 2020/21 under the previous REF to 33.05 per cent in 2021/22, although the actual funding the institutions received increased due to an overall increase in funding levels and the five universities remained (with Manchester) the top six institutions by share of funding. The LSE saw a decrease in actual funding of 9.03 per cent, leading to a 0.28 percentage point fall in its share of funding to 0.85 per cent, placing it below the post-92 Northumbria University.

In 2004, the G5 universities consisting of Cambridge, Imperial, LSE, Oxford and UCL were accused of secretly coordinating bids for an increased share of any extra money made available in the government's summer 2004 spending review. The objective was to secure extra state funding above the £3,000 student top-up fees planned in England from 2006 to cover the full costs of home and European Union undergraduates on their courses. This has been attributed to the universities stating they are offering no cheap courses, and that they would have to reduce their intake of UK students without the additional income.

The balance of funding between the 'golden triangle' and the rest of the UK has been questioned, and was specifically included in the terms of reference for an enquiry in 2018 by the House of Commons Science and Technology Select Committee. According to defenders of the level of funding going to the golden triangle institutions, "The apparent concentration of research in the golden triangle is little more than a reflection of the distribution of people in the UK". Analysis of grant proposals to Research Councils UK between 2012–13 and 2016–17 has shown that golden triangle institutions do not have unusually high success rates (two are actually below the expected range), but that the northern universities of Durham, Lancaster and York do. In February 2022, the UK Government announced as part of its "Levelling Up" white paper that public investment outside of the south east would increase by 40% by 2030, despite warnings from leaders of research-intensive universities that this could reduce the importance of scientific excellence in funding decisions. A report by the Higher Education Policy Institute in 2024 found that research quality was no higher in the golden triangle than elsewhere, concluding that the higher funding levels in the golden triangle "may reflect a retained and somewhat toxic historical and cultural bias towards particular institutions", with lower levels of research activity outside of the southeast reflecting lower levels of investment.