Roger Jason Stone Jr. (born Roger Joseph Stone Jr.; August 27, 1952) is an American conservative political consultant and lobbyist. Since the 1970s, he has worked on the campaigns of Republican politicians, including Richard Nixon, Ronald Reagan, Jack Kemp, Bob Dole, George W. Bush, and—most prominently—Donald Trump. Stone co-founded the lobbying firm Black, Manafort, Stone and Kelly in 1980 with Charles R. Black Jr. and Paul Manafort, later recruiting Peter G. Kelly in 1984.

Drawn to conservatism after reading Barry Goldwater's book The Conscience of a Conservative (1960), Stone supported Goldwater's 1964 presidential campaign as a child. He attended George Washington University but dropped out; while there, he was hired to spy on rival presidential campaigns during the Democratic Party presidential primaries for Nixon's 1972 campaign as part of a clandestine operation that became part of the Watergate scandal. Stone worked in Reagan's unsuccessful bid for president in 1976 and became the president of the Young Republicans in 1977. Known as the "keeper of the Nixon flame", he advised Nixon following his presidency. Stone continued to work for Reagan in his 1980 presidential campaign under the behest of John Sears and was "instrumental" to his 1984 campaign. Black, Manafort and Stone became one of the most prominent lobbying firms by 1990, although it gained notoriety for its clientele such as dictators.

In the early 1980s, Stone began working with Donald Trump through Black, Manafort and Stone, who was the firm's first client. He began working with Trump more directly in the 1990s as a lobbyist for the nascent Trump Hotels & Casino Resorts. In 1999, Stone became the campaign manager for Trump's 2000 presidential campaign. He served as an advisor for Trump's 2016 campaign until August 2015. Business partner Paul Manafort served as Trump's campaign manager. During his time working for Trump, Stone repeatedly communicated with WikiLeaks and its founder, Julian Assange. Despite his departure, Stone's support for Trump intensified in the years since and, in April 2016, he founded the pro-Trump activist group Stop the Steal. During the 2020 United States presidential election, he supported Trump once again; following Trump's loss to Joe Biden, Stone spread multiple unproven allegations of voter fraud. He was subpoenaed by the House Select Committee on the January 6 Attack in November 2021. Stone has reaffirmed his support for Trump in his 2024 campaign.

Stone's communications with Russian officials and WikiLeaks received scrutiny. During the 2016 presidential election, John Podesta, the chairman for Hillary Clinton's 2016 presidential campaign, accused him of having knowledge of Podesta's emails before they were released. Conservative publication The Washington Times reported that Stone had contact with Guccifer 2.0, the persona of a Russian hacker or hacker group that gained access into the servers of the Democratic National Committee. On January 25, 2019, Stone's Fort Lauderdale, Florida home was raided by the Federal Bureau of Investigation and he was arrested in connection to Robert Mueller's special counsel investigation. He was charged with one count of witness tampering, one count of obstructing an official proceeding, and five counts of making false statements to Congress and indicted in November 2019; Stone was sentenced to 40 months in prison. His term was commuted by Trump in July 2020 and he was pardoned on December 23, 2020.

Roger Joseph Stone Jr. was born on August 27, 1952 in Norwalk, Connecticut, the oldest of three children. His parents, of Italian and Hungarian descent, were Gloria Rose (Corbo) Stone and Roger J. Stone. As a child, the Stones moved to Lewisboro, New York. His mother wrote for the local newspaper and was a Cub Scout den mother, while his father ran a well drilling company and was a member of the Vista Fire Department. According to Stone, his family was middle class, blue collar, and Catholic. He took an active interest in politics early on; in an interview with The Washington Post, he recounted telling classmates that Richard Nixon was in favor of school on Saturdays to further John F. Kennedy's presidential campaign during the 1960 United States presidential election, calling it his "first political trick". Stone believed that, although his parents were Republicans, they held a special admiration for Kennedy because he was a Catholic.

Stone became particularly involved in politics when a neighbor gave him a copy of Barry Goldwater's book The Conscience of a Conservative (1960), convincing him to become a conservative. He took to wearing a Goldwater button to school and ran errands for the local Republican headquarters after school despite being seen as an outcast by his peers. Stone's bedroom was decorated "like the Goldwater headquarters", adorned with posters of Goldwater and vice presidential nominee William E. Miller. When Goldwater lost the 1964 presidential election to Lyndon B. Johnson, he was "crushed", didn't eat for days, and cried. A year later, Stone began commuting to New York to support the mayoral campaign of William F. Buckley, Jr., founder of the National Review. Buckley's son, Christopher Buckley, reportedly threw him into a hotel swimming pool while attending the 1968 Republican National Convention, a claim Buckley denies. Stone was first introduced to former president Richard Nixon through his mentor, Connecticut governor and ambassador John Davis Lodge. He met Nixon in 1967; Lodge appointed him as the chairman of Youth for Nixon a year later.

Stone attended John Jay High School in Westchester County, where he ran for president of his freshmen class. He became vice president of the student body his junior year and president his senior year. According to his mother, Stone's extravagant campaigns earned him an honorary athletic letter, the only one in the school's history. Social studies teacher John Wirchansky said people bunted for him and walked down the aisles "in hats". In an interview with The New York Times, he said, "I built alliances and put all my serious challengers on my ticket. Then I recruited the most unpopular guy in the school to run against me. You think that's mean? No, it's smart." In 1970, Stone enrolled in George Washington University and moved to Washington, D.C.. He became president of the District of Columbia charter of the Young Republicans and regularly attended Young Americans for Freedom meetings while his roommates, according to Stone, "[protested] the Vietnam War". Stone claimed to have attended George Washington University for five years and majored in political science, but the university's registrar shows that he only completed two years and signed up for continuous enrollment, but only completed one more course the following year. He later stated that the courses were "not relevant to real life".

In 1971, Stone was dispatched by Nixon campaign aide Herbert Porter to deliver a pamphlet prepared by aides Porter, Pat Buchanan, and Ken Khachigian criticizing Democratic presidential hopeful Edmund Muskie to Democrat George McGovern's headquarters and the Manchester Union-Leader. On another occasion, he made a contribution posing as the Young Socialist Alliance and delivered the receipt to New Hampshire news outlets. In 1972, the Committee for the Re-Election of the President sought a full-time "prankster". Stone convinced deputy director Jeb Stuart Magruder to give him a job as a scheduler. Porter enlisted Stone to identify an operative who could penetrate the campaigns of Democratic candidates. His choice was a Kentucky campaign worker named Michael McMinoway who worked under the alias Jason Rainer. McMinoway worked on the campaigns of three Democratic candidates, including McGovern and Muskie. Nixon would go on to win the 1972 presidential election and Stone worked in the Office of Economic Opportunity. Amid the Watergate scandal, he worked on the Virginia gubernatorial campaign for Mills Godwin and became a junior staffer for senator Bob Dole in December 1973. Despite being cleared by the Senate Watergate Committee and the Federal Bureau of Investigation, the scandal cost Stone his position with Dole and he was viewed as a pariah. Stone's departure came after columnist Jack Anderson called him a "dirty trickster", although he contends that he was given notice before the column appeared.