George Gill Green (January 16, 1842 – February 26, 1925) was a patent medicine entrepreneur, and Union surgeon in the American Civil War.

He enlisted in the 142nd Illinois Volunteer Infantry Regiment and was active from 1864 to 1865 during the American Civil War.

Green created a marketing campaign involving mass mailings of free samples and the distribution of thousands of his almanacs.

Green completed a summer home, Kil Kare Castle, in 1895 at Lake Hopatcong in New Jersey.

His patent medicine business declined after the passage of the Pure Food and Drug Act in 1906, and by 1916 his company's products were discontinued.