Whistlejacket is an oil on canvas painting from about 1762 by the British artist George Stubbs showing the Marquess of Rockingham's racehorse approximately at life-size, rearing up against a plain background. The canvas is large, lacks any other content except some discreet shadows, and Stubbs has paid precise attention to the details of the horse's appearance. It has been described in The Independent as "a paradigm of the flawless beauty of an Arabian thoroughbred". The Fitzwilliam family, heirs of the childless Rockingham, retained the painting until 1997 when funding from the Heritage Lottery Fund allowed the National Gallery, London to acquire it for £11 million.