(b. ca. 1734, ?, d. 1783, St. Petersburg)
English portrait painter. He studied under Benjamin Wilson and afterwards under Raphael Mengs at Rome where he became acquainted with the Earl of Northampton, whom he accompanied to Venice. During his stay in Venice he painted the portraits of the Duke of York and other English gentlemen, in a conversation piece (Royal Collection, London), which was exhibited at Spring Gardens in 1763. In 1765 Brompton settled in London and established a good practice with small-scale works in the manner of Johann Zoffany. He was an exhibitor at the Society of Arts and Royal Academy between the years 1767 and 1780.
In 1772 he painted the Prince of Wales, full length, in the robes of the Garter, and his brother, Prince Frederick, in the robes of the Bath. His best known portrait is that of William Pitt, first earl of Chatham (1772; Chevening, Kent), in which the great statesman is represented half-length, in peer's robes, standing with his right hand raised to his breast and his left arm extended. In the gallery of Greenwich Hospital is a half-length portrait by him of Admiral Sir Charles Saunders.
Brompton's extravagant habits led him into difficulties, and caused his confinement in the king's bench prison for debt; but being appointed portrait-painter to the Empress of Russia, he was released and went to St. Petersburg, where he died in 1782.