The National Gallery is an art museum on Trafalgar Square, London, United Kingdom. Founded in 1824, it houses a collection of over 2,300 paintings dating from the mid-13th century to 1900. The gallery is an exempt charity, and a non-departmental public body of the Department for Culture, Media and Sport. Its collection belongs to the public of the United Kingdom and entry to the main collection (though not some special exhibitions) is free of charge.

Unlike comparable art museums in continental Europe, the National Gallery was not formed by nationalising an existing royal or princely art collection. It came into being when the British government bought 38 paintings from the heirs of John Julius Angerstein, an insurance broker and patron of the arts, in 1824. After that initial purchase the Gallery was shaped mainly by its early directors, notably Sir Charles Lock Eastlake, and by private donations, which comprise two thirds of the collection. The resulting collection is small in size, compared with many European national galleries, but encyclopaedic in scope; most major developments in Western painting "from Giotto to Cézanne" are represented with important works. It used to be claimed that this was one of the few national galleries that had all its works on permanent exhibition, but this is no longer the case.