Seth Crittenden Moffatt (August 10, 1841 – December 22, 1887) was a politician from the U.S. state of Michigan.

He was admitted to the bar and commenced practice in Traverse City, Michigan.

He served as prosecuting attorney for Grand Traverse and Leelanau Counties for ten years.

In 1884, Moffatt was elected as a Republican from Michigan's 11th congressional district to the 49th Congress.

Seth Moffatt was a resident of Northport and is interred at Oakwood Cemetery of Traverse City.