John Milton Bigelow (June 23, 1804 – July 18, 1878) was an American physician and botanist. He had a successful medical practice, and also, a keen interest in botany - especially native plants with medical applications. He participated as a botanist and surgeon on two important expeditions through the American Southwest—the Mexican Boundary Survey and the 35th Parallel Expedition for the Pacific Railroad Surveys. He also amassed a significant collection of California plants that yielded many new species. He communicated his botanical results with the three top American botanists of the day, John Torrey, Asa Gray, and George Engelmann. Many of his botanical discoveries were named after or by him. He contributed to the botanical and medical literature of his day.