John Stephen Monagan (December 23, 1911 – October 23, 2005) was a Connecticut politician, lawyer, and author.

In 1958, he was elected Congressman from a district including Waterbury and served in the House of Representatives from 1959 until 1973, leaving after being defeated for re-election in 1972.

After leaving Congress, Monagan practiced as a lawyer in Washington, D.C., and was active in amateur music and in charitable causes.

He continued to be active into his nineties as a writer and book reviewer; a month before his death, he spoke at a symposium honoring Anthony Powell's centenary at Georgetown University.

His son-in-law was playwright and theater performer Trav S.D., who was married to his daughter Susan.