Barry Morris Goldwater (January 2, 1909 – May 29, 1998) was an American politician and United States Air Force major general who was a five-term U.S. Senator from Arizona (1953–1965, 1969–1987) and the Republican Party nominee for president of the United States in 1964. Goldwater is the politician most often credited with having sparked the resurgence of the American conservative political movement in the 1960s. Despite his loss of the 1964 U.S. presidential election in a landslide, many political pundits and historians believe he laid the foundation for the conservative revolution to follow, as the grassroots organization and conservative takeover of the Republican Party began a long-term realignment in American politics, which helped to bring about the "Reagan Revolution" of the 1980s. He also had a substantial impact on the American libertarian movement.

Goldwater was born in Phoenix in what was then the Arizona Territory, where he helped manage his family's department store. Upon the U.S. entry into World War II, Goldwater received a reserve commission in the United States Army Air Force. He trained as a pilot and was assigned to the Ferry Command, a newly formed unit that flew aircraft and supplies to war zones worldwide. After the war, Goldwater was elected to the Phoenix City Council in 1949 and won election to the U.S. Senate in 1952.

In the Senate, Goldwater rejected the legacy of the New Deal and, along with the conservative coalition, fought against the New Deal coalition. Goldwater also had a reputation as a "maverick" for challenging his party's moderate to liberal wing on policy issues. A member of the NAACP and active supporter of desegregation in Phoenix, Goldwater supported the Civil Rights Acts of 1957 and 1960 and the 24th Amendment to the U.S. Constitution, but, in a decision that he later said anguished him because of his belief in racial equality, he opposed the Civil Rights Act of 1964 on the basis that two of its provisions, specifically Title II and Title VII, were unconstitutional and a potential overreach of the federal government. In 1964, Goldwater mobilized a large conservative constituency to win the Republican presidential primaries. Although raised as an Episcopalian, Goldwater was the first candidate of Jewish descent (through his father) to be nominated for president by a major American party. Goldwater's platform ultimately failed to gain the support of the electorate and he lost the 1964 presidential election to incumbent Democrat Lyndon B. Johnson by one of the largest margins in history. Goldwater returned to the Senate in 1969 and specialized in defense and foreign policy. As an elder statesman of the party, Goldwater, who was respected by his colleagues for his honor and dedication to principle, successfully urged President Richard Nixon to resign in 1974 when evidence of a cover-up in the Watergate scandal became overwhelming and impeachment was imminent.

Goldwater narrowly won re-election in 1980 for what would be his final and most influential term in the Senate. In 1986, Goldwater oversaw passage of the Goldwater–Nichols Act, arguably his most significant legislative achievement, which strengthened civilian authority in the Department of Defense. The following year, he retired from the Senate and was succeeded by Congressman John McCain, who praised his predecessor as the man who "transformed the Republican Party from an Eastern elitist organization to the breeding ground for the election of Ronald Reagan". Goldwater strongly supported the 1980 presidential campaign of Reagan, who had become the standard-bearer of the conservative movement after his "A Time for Choosing" speech. Reagan reflected many of the principles of Goldwater's earlier run in his campaign. The Washington Post columnist George Will took note of this, writing: "We ... who voted for him in 1964 believe he won, it just took 16 years to count the votes".

Goldwater's views on social and cultural issues grew increasingly libertarian as he neared the end of his career. After leaving the Senate, Goldwater's views on social issues cemented as libertarian. He criticized the "money-making ventures by fellows like Pat Robertson and others [in the Republican Party] who are trying to ... make a religious organization out of it." In his later years, he supported homosexuals serving openly in the military, environmental protection, gay rights, abortion rights, adoption rights for same-sex couples, and the legalization of medicinal marijuana.