Claire Conner McCaskill (born July 24, 1953) is an American politician who served as a United States senator from Missouri from 2007 to 2019 and as State Auditor of Missouri from 1999 to 2007.

McCaskill is a native of Rolla, Missouri. She graduated from the University of Missouri and the University of Missouri School of Law. A member of the Democratic Party, McCaskill served as a member of the Missouri House of Representatives from 1983 to 1989, as Jackson County Prosecutor from 1993 to 1998, and as the 34th State Auditor of Missouri from 1999 to 2007. She ran for Governor of Missouri in the 2004 election, defeating Democratic incumbent Bob Holden in the Democratic primary and losing to Republican Matt Blunt in a close general election.

McCaskill was elected to the U.S. Senate in 2006, the first woman to be elected U.S. senator from Missouri (Jean Carnahan was appointed upon the death of her husband). Re-elected in 2012, McCaskill was defeated in 2018 by Republican challenger Josh Hawley. As of February 2019, McCaskill is a political analyst for MSNBC and NBC and a visiting fellow at the University of Chicago Institute of Politics.