John Russell "Russ" Carnahan (born July 10, 1958) is an American politician from the U.S. State of Missouri currently serving his third term in the U.S. House of Representatives. A Democrat, he represents Missouri's 3rd congressional district (map), which includes the southern third of the city of St. Louis (known as South City) and most of the southern St. Louis suburbs including most of Jefferson County and all of Ste. Genevieve County. Some cities located in the district include: Webster Groves, Mehlville, Affton, and Oakville (as part of South St. Louis City), and the southern suburbs of Arnold, Herculaneum, Pevely, Crystal City, Barnhart, Imperial, and Festus, as well as Ste. Genevieve in the neighboring Ste. Genevieve County.

John Russell Carnahan was born on July 10, 1958 in Columbia, Missouri. and raised in Rolla, Missouri He is the son of the late Mel Carnahan, the former Governor of Missouri and posthumous U.S. Senator-elect, and Jean Carnahan who was appointed to the U.S. Senate to fill the seat to which her husband was posthumously elected. Russ Carnahan is a recipient of the Eagle Scout Award. His sister Robin Carnahan was elected to the office of Secretary of State in 2004 and again in 2008 in which she received more votes cast for a single candidate in the state's history. His brother Randy was killed in the same plane crash that took the life of his father. Russ Carnahan received a bachelor's degree and a Juris Doctor degree from the University of Missouri. He worked as a private practice attorney prior to entering politics.

Carnahan is a member of the New Democrat Coalition.