OK Computer is the third studio album by the English rock band Radiohead, released on 21 May 1997. With their producer, Nigel Godrich, Radiohead recorded most of OK Computer in their rehearsal space in Oxfordshire and the historic mansion of St Catherine's Court in Bath in 1996 and early 1997. They distanced themselves from the guitar-centred, lyrically introspective style of their previous album, The Bends. OK Computer's abstract lyrics, densely layered sound and eclectic influences laid the groundwork for Radiohead's later, more experimental work.

The lyrics depict a dystopian, futuristic world fraught with rampant consumerism, capitalism, social and modern alienation, emotional isolation and political malaise, with overall themes like transport, technology, insanity, death, modern British life, globalisation and anti-capitalism; in this capacity, OK Computer is said by some to have prescient insight into the mood of 21st-century life. The band used unconventional production techniques, including natural reverberation, and no audio separation. Strings were recorded at Abbey Road Studios in London. Most of the album was recorded live.

Despite lowered sales estimates by EMI, who deemed it uncommercial and difficult to market, OK Computer reached number one on the UK Albums Chart and debuted at number 21 on the Billboard 200, Radiohead's highest album entry on the US charts at the time, and was soon certified five times platinum in the UK by the British Phonographic Industry (BPI) and double platinum in the US by the Recording Industry Association of America (RIAA). "Paranoid Android", "Karma Police", "Lucky" and "No Surprises" were released as singles. The album expanded Radiohead's international popularity and has sold at least 7.8 million units worldwide.

OK Computer received acclaim and has been cited as one of the greatest albums of all time. It was nominated for Album of the Year and won Best Alternative Music Album at the 1998 Grammy Awards. It was also nominated for Best British Album at the 1998 Brit Awards. The album initiated a stylistic shift in British rock away from Britpop toward melancholic, atmospheric alternative rock that became more prevalent in the next decade. In 2014, it was added by the US Library of Congress to the National Recording Registry. A remastered version with additional tracks, OKNOTOK 1997 2017, was released in 2017. In 2019, in response to an internet leak, Radiohead released MiniDiscs [Hacked], comprising hours of additional material.