The Blue Boy (c. 1770) is an oil painting by Thomas Gainsborough that now resies in the Huntington Library, San Marino, California. The painting itself is on a fairly large canvas for a portrait that measures 48 inches wide by 70 inches tall. Perhaps Gainsborough's most famous work, it is thought to be a portrait of Jonathan Buttall, the son of a wealthy hardware merchant. Gainsborough had originally painted something different on the canvas but then decided to paint the portrait of the blue boy over it. It is a historical costume study as well as a portrait: the youth in his 17th-century apparel is regarded as Gainsborough's homage to Anthony Van Dyck, and in particular is very close to Van Dyck's portrait of Charles II as a boy (below).