Spencer Truman Olin (August 20, 1900 - April 14, 1995) was an American businessman and philanthropist. He was an executive of the Olin Corporation, founded in 1892 by his father, Franklin W. Olin, eventually serving as first vice president of Olin Industries, though he reduced his involvement with the company after its 1954 merger with Mathieson.

He was raised in Alton, Illinois. In 1921 he graduated from