Howard Brush Dean III (born November 17, 1948) is an American politician and physician from the U.S. state of Vermont. A Democrat, Dean was elected to the Vermont House of Representatives in 1982 and was elected lieutenant governor in 1986. Both were part-time positions that enabled him to continue practicing medicine. In 1991, Dean became Governor of Vermont when Richard A. Snelling died in office. Dean was subsequently elected to five two-year terms, serving as governor from 1991 to 2003 making him the second longest-serving Governor in Vermont history. Dean served as chairman of the National Governors Association from 1994 to 1995; during his term, Vermont paid off much of its public debt and had a balanced budget 11 times, lowering income taxes twice. Dean also oversaw the expansion of the "Dr. Dynasaur" program, which ensures universal health care for children and pregnant women in the state.

An early frontrunner in the 2004 Democratic presidential nomination, Dean denounced the 2003 invasion of Iraq along with Democrats who he felt should have more strongly opposed the Bush Administration, pioneered the use of the Internet in campaigning and showed strong fundraising ability; however, he eventually lost the nomination to Senator John Kerry of Massachusetts.

Dean formed the organization Democracy for America and later was elected chairman of the Democratic National Committee in February 2005.