John Plankinton (March 11, 1820 – March 29, 1891) was an American businessman. He is noted for expansive real estate developments in Milwaukee, including the luxurious Plankinton House Hotel designed as an upscale residence for the wealthy. He was involved with railroading and banking. The Plankinton Bank he developed became the leading bank of Milwaukee in his lifetime. He was involved in the development of the Milwaukee City Railroad Company, an electric railway.