Jacob Viner (May 3, 1892 - September 12, 1970) was a noted economist. He was born in Montreal, Canada and attended McGill University. He later moved to the Harvard University and then in 1916 to the University of Chicago where he was based until 1946 then leaving for Princeton University.

He is noted for a wide range of contributions to many areas of economics. He developed the basic model of the firm, devising the long and short run cost curves that are still a staple.

Viner was a noted opponent of John Maynard Keynes during the Great Depression. While he agreed with the policies of government spending that Keynes pushed for, Viner argued that Keynes' analysis was flawed and would not stand in the long run.

He also made important contributions to the study of international trade and to economic history.

Viner often left academia to play a role in government, doing so frequently throughout his career.

At both Chicago and Princeton, Viner had a reputation as being one of the toughest professors, and many students were terrified by the prospect of studying under him.