John Henry Wonnacott CBE (born 1940, London, England) is a British painter.
Wonnacott trained at the Slade School of Fine Art during 1958–63. He then moved to Southend-on-Sea, Essex, and still lives there. His solo exhibitions include shows at the Scottish National Portrait Gallery in Edinburgh (1986) and the National Portrait Gallery in London (2000). He has also had artworks exhibited at the Barbican Centre, the Royal Academy, and the Tate Gallery, all in London.
In 1997, Wonnacott painted the British prime minister John Major. In 2000, he painted the British Royal Family in a 12-foot tall artwork.
Wonnacott is a Commander of the Order of the British Empire (CBE), awarded in 2000. He was the 2005 winner of the Ondaatje Prize for portraiture.