John Courts Bagby (born January 24, 1819) was a Democratic member of the United States House of Representatives from Illinois. He represented Illinois’s 10th Congressional District and served a single term in Congress. His tenure in the U.S. House marked his role in national politics during the mid-1870s.

Bagby served as a Representative from December 6, 1875, to March 3, 1877. During this period, he was a historical member of Congress from Illinois, aligned with the Democratic Party. He held no additional listed congressional offices or committee assignments in the available record, and his service in the House concluded after one term.