Joseph Mallord William Turner RA (23 April 1775 – 19 December 1851), known in his time as William Turner, was an English Romantic painter, printmaker and watercolourist. He is known for his expressive colouring, imaginative landscapes and turbulent, often violent marine paintings. His artistic style developed over his lifetime, moving away from Romanticism—bypassing the following rising style of Realism—and, instead, with his later works being a significant precursor of and presaging the later Impressionist and Abstract Art movements that arose in the decades after his death. He left behind more than 550 oil paintings, 2,000 watercolours, and 30,000 works on paper. He was championed by the leading English art critic John Ruskin from 1840, and is today regarded as having elevated landscape painting to an eminence rivaling history painting.

Turner was born in Maiden Lane, Covent Garden, London, to a modest lower-middle-class family and retained his lower-class accent, while assiduously avoiding the trappings of success and fame. A child prodigy, Turner studied at the Royal Academy of Arts from 1789, enrolling when he was 14, and exhibited his first work there at 15. During this period, he also served as an architectural draftsman. He earned a steady income from commissions and sales, which he often only begrudgingly accepted owing to his troubled and contrary nature. He opened his own gallery in 1804 and became professor of perspective at the academy in 1807, where he lectured until 1828. He travelled around Europe from 1802, typically returning with voluminous sketchbooks.

Intensely private, eccentric, and reclusive, Turner was a controversial figure throughout his career. He did not marry, but fathered two daughters, Evelina (1801–1874) and Georgiana (1811–1843), by the widow Sarah Danby. He became more pessimistic and morose as he got older, especially after the death of his father in 1829; when his outlook deteriorated, his gallery fell into disrepair and neglect, and his art intensified. In 1841, Turner rowed a boat into the Thames so he could not be counted as present at any property in that year's census. He lived in squalor and poor health from 1845, and died in London in 1851 aged 76. Turner is buried in St Paul's Cathedral, London.

There are reasons to question the accepted location and birth date for Turner:

"He sometimes talked of being born in the same year as Napolean and the Duke of Wellington" This would put Turner's birth date as 1769.

"As the birth place of Turner has recently appeared to some persons a matter of doubt, I may here observe that he was born at Barnstaple, and neither in Maiden-lane nor at South Molton, if his own words go for anything." Cyrus Redding Fraser's Magazine February 1852.

Turner's father William Turner (1745–1829) moved to London around 1770 from South Molton, Devon.

Joseph Mallord William Turner was born on 23 April 1775 and baptised on 14 May. He was born in Maiden Lane, Covent Garden, in London. His father was a barber and wig maker. His mother, Mary Marshall, came from a family of butchers. A younger sister, Mary Ann, was born in September 1778 but died in August 1783.