Joseph Raymond McCarthy (November 14, 1908 May 2, 1957) was an American politician who served as a Republican U.S. Senator from the state of Wisconsin from 1947 until his death in 1957. Beginning in 1950, McCarthy became the most visible public face of a period in the United States in which Cold War tensions fueled fears of widespread communist subversion. He is known for alleging that numerous communists and Soviet spies and sympathizers had infiltrated the United States federal government, universities, film industry, and elsewhere. Ultimately, the smear tactics that he used led him to be censured by the U.S. Senate. The term "McCarthyism", coined in 1950 in reference to McCarthy's practices, was soon applied to similar anti-communist activities. Today, the term is used more broadly to mean demagogic, reckless, and unsubstantiated accusations, as well as public attacks on the character or patriotism of political opponents.Born in Grand Chute, Wisconsin, McCarthy commissioned into the Marine Corps in 1942, where he served as an intelligence briefing officer for a dive bomber squadron. Following the end of World War II, he attained the rank of major. He volunteered to fly twelve combat missions as a gunner-observer. These missions were generally safe, and after one where he was allowed to shoot as much ammunition as he wanted to, mainly at coconut trees, he acquired the nickname "Tail-Gunner Joe". Some of his claims of heroism were later shown to be exaggerated or falsified, leading many of his critics to use "Tail-Gunner Joe" as a term of mockery.McCarthy successfully ran for the U.S. Senate in 1946, defeating Robert M. La Follette Jr. After three largely undistinguished years in the Senate, McCarthy rose suddenly to national fame in February 1950, when he asserted in a speech that he had a list of "members of the Communist Party and members of a spy ring" who were employed in the State Department. In succeeding years after his 1950 speech, McCarthy made additional accusations of Communist infiltration into the State Department, the administration of President Harry S. Truman, the Voice of America, and the U.S. Army. He also used various charges of communism, communist sympathies, disloyalty, or sex crimes to attack a number of politicians and other individuals inside and outside of government. This included a concurrent "Lavender Scare" against suspected homosexuals; as homosexuality was prohibited by law at the time, it was also perceived to increase a person's risk for blackmail.With the highly publicized ArmyMcCarthy hearings of 1954, and following the suicide of Wyoming Senator Lester C. Hunt that same year, McCarthy's support and popularity faded. On December 2, 1954, the Senate voted to censure Senator McCarthy by a vote of 6722, making him one of the few senators ever to be disciplined in this fashion. He continued to speak against communism and socialism until his death at the age of 48 at Bethesda Naval Hospital in Bethesda, Maryland, on May 2, 1957. His death certificate listed the cause of death as "Hepatitis, acute, cause unknown". Doctors had not previously reported him to be in critical condition. Some biographers say this was caused or exacerbated by alcoholism.McCarthy is the last Republican to have held or won election to Wisconsin's Class I Senate seat.

McCarthyism is the practice of making accusations of subversion and treason, especially when related to communism and socialism. The term originally referred to the controversial practices and policies of U.S. Senator Joseph McCarthy (R-Wisconsin), and has its origins in the period in the United States known as the Second Red Scare, lasting from the late 1940s through the 1950s. It was characterized by heightened political repression and persecution of left-wing individuals, and a campaign spreading fear of alleged communist and socialist influence on American institutions and of espionage by Soviet agents. After the mid-1950s, McCarthyism began to decline, mainly due to Joseph McCarthy's gradual loss of public popularity and credibility after several of his accusations were found to be false, and sustained opposition from the U.S. Supreme Court led by Chief Justice Earl Warren on human rights grounds. The Warren Court made a series of rulings on civil and political rights that overturned several McCarthyist laws and directives, and helped bring an end to McCarthyism.What would become known as the McCarthy era began before McCarthy's rise to national fame. Following the breakdown of the wartime East-West alliance with the Soviet Union, and with many remembering the First Red Scare, President Harry S. Truman signed an executive order in 1947 to screen federal employees for possible association with organizations deemed "totalitarian, fascist, communist, or subversive", or advocating "to alter the form of Government of the United States by unconstitutional means." The following year, the Czech coup by the Czechoslovakian Communist Party heightened concern in the West about Communist parties seizing power and the possibility of subversion. In 1949, a high-level State Department official was convicted of perjury in a case of espionage, and the Soviet Union tested an atomic bomb. The Korean War started the next year, significantly raising tensions and fears of impending communist upheavals in the United States. In a speech in February 1950, McCarthy presented a list of alleged members of the Communist Party USA working in the State Department, which attracted substantial press attention, and the term McCarthyism was published for the first time in late March of that year in The Christian Science Monitor, along with a political cartoon by Herblock in The Washington Post. The term has since taken on a broader meaning, describing the excesses of similar efforts to crack down on alleged "subversive" elements. In the early 21st century, the term is used more generally to describe reckless and unsubstantiated accusations of treason and far-left extremism, along with demagogic personal attacks on the character and patriotism of political adversaries.

The primary targets of McCarthyist persecution were government employees, prominent figures in the entertainment industry, academics, left-wing politicians, and labor union activists. Suspicions were often given credence despite inconclusive and questionable evidence, and the level of threat posed by a person's real or supposed leftist associations and beliefs were often exaggerated. Many people suffered loss of employment and the destruction of their careers and livelihoods as a result of the crackdowns on suspected communists, and some were outright imprisoned. Most of these reprisals were initiated by trial verdicts that were later overturned, laws that were later struck down as unconstitutional, dismissals for reasons later declared illegal or actionable, and extra-judiciary procedures, such as informal blacklists by employers and public institutions, that would come into general disrepute, though by then many lives had been ruined. The most notable examples of McCarthyism include the investigations of alleged communists that were conducted by Senator McCarthy, and the hearings conducted by the House Un-American Activities Committee (HUAC).