Gilbert Stuart (né Stewart; December 3, 1755 – July 9, 1828) was an American painter born in the Rhode Island Colony who is widely considered one of America's foremost portraitists. His best-known work is an unfinished portrait of George Washington, begun in 1796, which is usually referred to as the Athenaeum Portrait. Stuart retained the original and used it to paint scores of copies that were commissioned by patrons in America and abroad. The image of George Washington featured in the painting has appeared on the United States one-dollar bill for more than a century and on various postage stamps of the 19th century and early 20th century.

Stuart produced portraits of about 1,000 people, including the first six Presidents. His work can be found today at art museums throughout the United States and the United Kingdom, including the Metropolitan Museum of Art and Frick Collection in New York City, the National Gallery of Art in Washington, D.C., the Philadelphia Museum of Art in Philadelphia, the National Portrait Gallery in Washington D.C., the National Portrait Gallery in London, England, the Worcester Art Museum in Worcester, Massachusetts, and the Boston Museum of Fine Arts.

Stuart was born on December 3, 1755, in Saunderstown, a village of North Kingstown in the Colony of Rhode Island and Providence Plantations, and he was baptized at Old Narragansett Church on April 11, 1756. He was the third child of Gilbert Stuart, a Scottish immigrant employed in the snuff-making industry, and Elizabeth Anthony Stuart, a member of a prominent land-owning family from Middletown, Rhode Island. Stuart's father owned the first snuff mill in America, which was located in the basement of the family homestead.

Stuart moved to Newport, Rhode Island, at the age of six, where his father pursued work in the merchant field. In Newport, he first began to show great promise as a painter. In 1770, he made the acquaintance of Scottish artist Cosmo Alexander, a visitor to the colonies who made portraits of local patrons and who became a tutor to Stuart. Under the guidance of Alexander, Stuart painted the portrait Dr. Hunter's Spaniels when he was 14; it hangs today in the Hunter House Mansion in Newport.

In 1771, Stuart moved to Scotland with Alexander to finish his studies; however, Alexander died in Edinburgh one year later. Stuart tried to maintain a living and pursue his painting career, but to no avail, so he returned to Newport in 1773.

Stuart's prospects as a portraitist were jeopardized by the onset of the American Revolution and its social disruptions. Although he was a patriot, he departed for England in 1775 following the example set by John Singleton Copley. His painting style during this period began to develop beyond the relatively hard-edged and linear style that he had learned from Alexander. He was unsuccessful at first in pursuit of his vocation, but he became a protégé of Benjamin West in 1777 and studied with him for the next six years. The relationship was beneficial, with Stuart exhibiting for the first time at the Royal Academy in spring of 1777.

By 1782, Stuart had met with success, largely due to acclaim for The Skater, a portrait of Sir William Grant. It was Stuart's first full-length portrait and, according to a rival, it belied the prevailing opinion that Stuart "made a tolerable likeness of a face, but as to the figure, he could not get below the fifth button'". Stuart said that he was "suddenly lifted into fame by a single picture".

The prices for his pictures were exceeded only by those of renowned English artists Joshua Reynolds and Thomas Gainsborough. Despite his many commissions, however, he was habitually neglectful of finances and was in danger of being sent to debtors' prison. In 1787, he fled to Dublin, Ireland where he painted and accumulated debt with equal vigor.