Chauncey Langdon Knapp (February 26, 1809 – May 31, 1898) was an American newspaperman and politician who served two terms as a U.S. Representative from Massachusetts from 1855 to 1859.

For a number of years, he was co-proprietor and editor of the State Journal, Vermont's main Anti-Masonic Party newspaper.

During the heated slavery debates in Congress, Senator Charles Sumner of Massachusetts was severely beaten by Congressman Preston Brooks of South Carolina on May 22, 1856.

In response, Congressmen Knapp delivered his first address on the floor of the House, a speech in which he said his constituents viewed the attack as an "audacious blow hurled at the great right of free opinion.

This article incorporates public domain material from the Biographical Directory of the United States Congress