Gilbert Stuart Newton RA was a British artist.
Newton was born in Halifax, Nova Scotia, the twelfth child and youngest son of Henry Newton, a customs official, and Ann, his wife, daughter of Gilbert Stuart, snuff manufacturer at Boston, Massachusetts, of Scottish descent, and sister to Gilbert Stuart the portrait painter. His parents left Boston in 1776 as the British withdrew; but on the death of his father in 1803 his mother returned with her family to Charlestown, near Boston.

Newton was intended for a commercial career, but was taken on as a pupil by his uncle, Gilbert Stuart. Newton came to Europe with an elder brother, and studied painting at Florence. In 1817 he visited Paris on his way to England and there met Charles Robert Leslie, as well as Washington Allston and David Wilkie. After visiting the Netherlands Newton went with Leslie to London, and entered as a student at the Royal Academy.

He revisited America for a short time and there married Sarah Williams Sullivan, granddaughter of James Swan (financier), Hepzibah Swan and James Sullivan (governor), returning to England with his wife. In 1827 he was elected into the National Academy of Design as an Honorary Academician. He was elected an associate of the Royal Academy in 1829 and an academician in 1832. Soon after his election to the Academy he started suffering from mental illness, and was placed in an asylum at Chelsea. He continued to paint there, where he died suffering from consumption, at Chelsea on 5 August 1835. He was buried in St Mary's Church Wimbledon. His grave is clear to see in the north end of the churchyard. His wife Sarah had returned to America with their daughter Annie Stewart Newton a few months before, and subsequently remarried.