John Jacob Astor (born Johann Jakob Astor; July 17, 1763 – March 29, 1848) was a German-born American businessman, merchant, real estate mogul, and investor who made his fortune mainly in a fur trade monopoly, by smuggling opium into China, and by investing in real estate in or around New York City. He was the first prominent member of the Astor family and the first multi-millionaire in the United States.

Born in Germany, Astor emigrated to England as a teenager and worked as a musical instrument manufacturer. He moved to the United States after the American Revolutionary War. Seeing the expansion of population to the west, he entered the fur trade and built a monopoly, managing a business empire that extended to the Great Lakes region and Canada, and later expanded into the American West and Pacific coast. Seeing a decline in demand due to changing European tastes, he got out of the fur trade in 1830, diversifying by investing in New York City real estate. Astor was highly wealthy and became a prominent patron of the arts. In proportion to GDP, he was one of the richest people in modern history.