Thomas M. Hannigan (May 30, 1940 – October 9, 2018) was an American businessman and politician.

He served in the United States Marine Corps from 1963 to 1966 and was commissioned a captain.

He moved to Fairfield, California and was in the real estate business.

Hannigan served in the California State Assembly from December 4, 1978 - November 30, 1996 and was a Democrat.

From 1999 to 2003, Hannigan served as the director of the California Department of Water Resources.