William Allen Rusher (July 19, 1923 – April 16, 2011) was an American lawyer, author, activist, and conservative columnist. He was one of the founders of the modern conservative movement and was one of its most prominent spokesmen for thirty years as publisher of National Review magazine, which was edited by William F. Buckley Jr. Historian Geoffrey Kabaservice argues that, "in many ways it was Rusher, not Buckley, who was the founding father of the conservative movement as it currently exists. We have Rusher, not Buckley, to thank for the populist, operationally sophisticated, and occasionally extremist elements that characterize the contemporary movement."

Rusher was born in Chicago in 1923. His family had not been especially political; his parents were moderate Republicans, and his paternal grandfather had been a socialist. In 1930, the family moved to the New York metropolitan area and lived on Long Island. Rusher entered Princeton University at sixteen and was active in student affairs, especially debate. He majored in political science. After graduation in 1943 and wartime service in the United States Army Air Corps, he attended Harvard Law School, where he founded and led the Harvard Young Republicans and from which he graduated in 1948. Until 1956, Rusher practiced corporate law at Shearman, Sterling & Wright, a Wall Street firm in New York City. He then served as associate counsel to the Senate Internal Security Subcommittee, under chief counsel Robert J. Morris, for seventeen months.

In these years, Rusher was also active in New York state and national Young Republican politics, helping F. Clifton White to lead an alliance in these organizations including the New York Young Republican Club. He came to the attention of William F. Buckley Jr., editor of the fledgling National Review, shortly after its founding in late 1955, when he wrote an essay for the Harvard Young Republican paper, titled "Cult of Doubt."

In mid-1957, William F. Buckley Jr. hired Rusher as publisher of National Review. At the magazine, he oversaw the business operations, but more importantly served as a link to the world of conservative and Republican politics. He held the rank although not the title of senior editor and as such was a full participant in its internal deliberations. At National Review, he advocated that the magazine develop and maintain a leadership role in the conservative movement. In doing this, Rusher sometimes disagreed with Buckley and senior editor James Burnham. In his philosophy of conservative politics and his belief in the urgent need for an active and unified movement to pursue conservative politics, he was especially close to another senior editor at the magazine, Frank Meyer.

Rusher was an early mentor of Young Americans for Freedom, founded in Connecticut with his assistance in 1960. He helped to found the Conservative Party of New York State in 1961, and the American Conservative Union in 1964. He was a mentor to young conservative activists from these early years into the 1990s.

In 1961, Rusher worked with Clif White and Congressman John Ashbrook to form the nucleus of what became U.S. Senator Barry M. Goldwater's campaign for the Republican nomination for the presidency in 1964, known as the Draft Goldwater Committee. Goldwater's victory in the bitterly fought nomination contest over New York Governor Nelson A. Rockefeller and the previously dominant moderate or liberal establishment in the Republican Party was the first stage in the rise to national power of the conservative movement. In December 1961, Rusher was a founding member of the American Committee for Aid to Katanga Freedom Fighters, a lobbying group which sought U.S. recognition of Katanga.

In 1966, Rusher together with Max Yergan became co-chairmen of the American-African Affairs Association (AAAA), which lobbied the United States to recognize Rhodesia. A major theme of the publications of the American-African Affairs Association was the black opponents of Rhodesia were controlled by either the Soviet Union or China, and to allow majority rule in Rhodesia would thus allow Communism to be established there. In a letter to the editor of The Nation in 1967, Rusher admitted that an overlap in topics and themes expressed by the AAAA and the Rhodesian Information Office was due to the fact that AAAA shared the same offices at 79 Madison Avenue in New York as the public relations firm of Marvin Liebman Associates, which had been hired by the Information Office to improve Rhodesia's image in America. As a part of his efforts to assist Rhodesia, Rusher introduced Kenneth Towsey, the head of the New York office of the Rhodesian Information Office, to various media personalities where Towsey made his case that Rhodesia, which was often pillared in the United States for its white supremacist policies, was just being misunderstood by the American media.

Beginning in the late 1950s and continuing well past his retirement from National Review at the end of the 1980s, Rusher was a very active public speaker on college campuses and in other forums, where he defended and advocated the conservative position. In the early 1970s, he was the main conservative representative on a PBS television debate show, The Advocates, which also featured the later governor of Massachusetts, Michael S. Dukakis, the 1988 Democratic presidential nominee. Rusher was also a commentator on ABC-TV's Good Morning America in the late 1970s and a regular radio commentator in the 1980s. Throughout Rusher's career, he was known as an aggressive and exceptionally skilled debater. However, in a 1971 debate, Rusher faced formidable opposition in linguist and prominent anti-war activist MIT professor Noam Chomsky; Rusher repeatedly interrupted Chomsky, who calmly and assertively answered his questions.