"Whistlejacket" is an 18th-century painting by which English artist?

George Stubbs (25 August 1724 – 10 July 1806) was an English painter, best known for his paintings of horses. Self-trained, Stubbs learnt his skills independently from other great artists of the eighteenth century such as Reynolds or Gainsborough. Stubbs' output includes history paintings, but his greatest skill was in painting animals, perhaps influenced by his love and study of anatomy.

His most famous work is probably "Whistlejacket", a painting of the thoroughbred race horse rising on his hind legs, commissioned by the 2nd Marquess of Rockingham, which is now in the National Gallery in London. This and two other paintings carried out for Rockingham break with convention in having plain backgrounds. Throughout the 1760s he produced a wide range of individual and group portraits of horses, sometimes accompanied by hounds. He often painted horses with their grooms, whom he always painted as individuals.