Joseph Manchin III (born August 24, 1947) is an American politician and businessman serving as the senior United States senator from West Virginia, a seat he has held since 2010. Manchin was the 34th governor of West Virginia from 2005 to 2010 and the 27th secretary of state of West Virginia from 2001 to 2005. He became the state's senior U.S. senator when Jay Rockefeller left office in 2015 and has since been West Virginia's only congressional Democrat. Before entering politics, Manchin helped found and was the president of Enersystems, a coal brokerage company his family owns and operates.

Manchin won the 2004 West Virginia gubernatorial election by a large margin and was reelected by an even larger margin in 2008. He won the 2010 special election to fill the Senate seat vacated by incumbent Democrat Robert Byrd's death with 53% of the vote, and in 2012 was elected to a full term with 61% of the vote. Manchin won a second term in 2018 with just under 50% of the vote. In both elections, he over-performed the Democratic presidential ticket by more than 40 percentage points. Since 2021, Manchin has been the only Democrat holding statewide or congressional office in West Virginia, and represents what is, by a large margin, the most Republican-leaning constituency of any Democrat in Congress.