Jonas 'Martin' Frost III (born January 1, 1942), American politician, was the Democratic representative to the U.S. House of Representatives for the Texas 24th congressional district from 1979 to 2004. He is married to Major General Kathryn Frost.
Born in Glendale, California, Frost grew up in Fort Worth, Texas. He graduated from the University of Missouri in 1964 with bachelor's degrees in journalism and history, later receiving his law degree from the Georgetown University Law Center in 1970.
Before going to law school, Frost worked as a newspaper reporter. Following his graduation he worked as a law clerk for Federal Judge Sarah T. Hughes of the Northern District of Texas and began a private practice.
Frost ran unsuccessfully for a seat in the House in 1974. He tried again successfully in 1978, becoming the second Jewish U.S. congressman from Texas since David Spangler Kaufman. Redistricting in 2003 by the Texas Legislature caused Frost to seek re-election in the newly redrawn 32nd district, where he lost to Pete Sessions.
He was the ranking member of the House Rules Committee.
In 2005, Martin Frost was a candidate for Chairman of the Democratic National Committee. He dropped out of the race on February 1.