Aberystwyth University (Welsh: Prifysgol Aberystwyth) is a public research university in Aberystwyth, Wales. Aberystwyth was a founding member institution of the former federal University of Wales. The university has over 8,000 students studying across three academic faculties and 17 departments.

Founded in 1872 as University College Wales, Aberystwyth, it became a founder member of the University of Wales in 1894, and changed its name to the University College of Wales, Aberystwyth. In the mid-1990s, the university again changed its name to become the University of Wales, Aberystwyth. On 1 September 2007, the University of Wales ceased to be a federal university and Aberystwyth University became independent again. The annual income of the institution for 2022–2023 was £130.8 million of which £22.2 million was from research grants and contracts, with an expenditure of £127.8 million.

In the middle of the 19th century, eminent Welsh people were advocating the establishment of a university in the principality of Wales. One of these, Thomas Nicholas, whose book, Middle and High Class Schools, and University Education for Wales (1863), is said to have "exerted great influence on educated Welshmen".

Funded through public and private subscriptions, and with five regional committees (London, Manchester, Liverpool, North and South Wales) guaranteeing funds for the first three years' running costs, the university opened in October 1872 with 26 students. Thomas Charles Edwards was the principal. In October 1875, chapels in Wales raised the next tranche of funds from over 70,000 contributors. Until 1893, when the college joined the University of Wales as a founder member, students applying to Aberystwyth sat the University of London's entrance exams. Women were admitted in 1884.

In 1885, a fire damaged what is now known as the Old College, Aberystwyth, and in 1897 the first 14 acres of what became the main Penglais campus were purchased. Incorporated by royal charter in 1893, the university installed Albert Edward, Prince of Wales, as chancellor in 1896, the same year it awarded an honorary degree to the former British prime minister, William Gladstone.

The university's coat of arms dates from the 1880s. The shield features two red dragons to symbolise Wales, and an open book to symbolise learning. The crest, an eagle or phoenix above a flaming tower, may signify the college's rebirth after the 1885 fire. The motto is Nid Byd, Byd Heb Wybodaeth ('a world without knowledge is no world at all').

In the early 1900s, the university added courses that included law, applied mathematics, pure mathematics and botany. The Department for International Politics, which Aberystwyth says is the oldest such department in the world, was founded in 1919. By 1977, the university's staff included eight Fellows of the Royal Society, such as Gwendolen Rees, the first Welsh woman to be elected an FRS.

The Department of Sports and Exercise Science was established in 2000. Joint honours psychology degrees were introduced in September 2007, and single honours psychology in 2009.