The Wellcome Trust is a charitable foundation focused on health research based in London, United Kingdom. It was established in 1936 with legacies from the pharmaceutical magnate Henry Wellcome to fund research to improve human and animal health. The aim of the Trust is to "support science to solve the urgent health challenges facing everyone." It had a financial endowment of £29.1 billion in 2020, making it the fourth wealthiest charitable foundation in the world. In 2012, the Wellcome Trust was described by the Financial Times as the United Kingdom's largest provider of non-governmental funding for scientific research, and one of the largest providers in the world. According to their annual report, the Wellcome Trust spent GBP £1.1 billion on charitable activities across their 2019/2020 financial year. According to the OECD, the Wellcome Trust's financing for 2019 development increased by 22% to US$327 million.

Sir Henry Solomon Wellcome was an American pharmaceutical entrepreneur. He founded the pharmaceutical company Burroughs Wellcome & Company with his colleague Silas Burroughs in 1880, which is one of the four large companies to eventually merge to form GlaxoSmithKline. He left a large amount of capital for charitable work in his will, which was used to form the Wellcome Trust, one of the world's largest medical charities. He was a keen collector of medical artefacts which are now managed by the Science Museum, London, and a small selection of which are displayed at the Wellcome Collection.