Jean Carnahan (born December 20, 1933) was a member of the United States Senate from 2001 to 2003. She ascended to the Senate under unusual conditions.

Jean Carnahan's husband Mel, then the governor of Missouri, had been running against the then-incumbent Senator from Missouri, John Ashcroft. Several weeks before election day, Mel Carnahan was killed in a plane crash (along with his son Randy Carnahan and Chris Sifford, a campaign advisor), but his name could not be removed from the ballot due to Missouri election law. Acting Governor Roger B. Wilson announced that he would appoint Jean Carnahan if Mel Carnahan won the election, and Jean Carnahan agreed. Under Missouri law, Jean Carnahan would only serve until a special election could be held in 2002. Mel Carnahan won the election, and Jean Carnahan was appointed to the Senate in 2001.

In 2002, Carnahan tried to win the seat in her own right, but failed to do so; she was defeated by Republican James Talent.

Except for her time in the Senate, Carnahan has never held public office.