Harry Mason Reid Jr. (/riːd/; December 2, 1939 – December 28, 2021) was an American lawyer and politician who served as a United States senator from Nevada from 1987 to 2017. He led the Senate Democratic Caucus from 2005 to 2017 and was the Senate Majority Leader from 2007 to 2015.

After earning an undergraduate degree from Utah State University and a Juris Doctor degree from George Washington University, Reid began his public career as the city attorney for Henderson, Nevada, before being elected to the Nevada Assembly in 1968. Gubernatorial candidate Mike O'Callaghan, Reid's former boxing coach, chose Reid as his running mate in 1970; following their victory Reid served as the 25th lieutenant governor of Nevada from 1971 to 1975. After being defeated in races for the United States Senate and mayor of Las Vegas, Reid served as chairman of the Nevada Gaming Commission from 1977 to 1981. From 1983 to 1987, Reid represented Nevada's 1st district in the United States House of Representatives.

Reid was elected to the United States Senate in 1986 and served in the Senate from 1987 to 2017. He served as the Senate Democratic whip from 1999 to 2005 before succeeding Tom Daschle as Senate Minority Leader. The Democrats won control of the Senate after the 2006 United States Senate elections, and Reid became the Senate Majority Leader in 2007. He held that position for the final two years of George W. Bush's presidency and for the first six years of Barack Obama's presidency. As majority leader, Reid helped pass major legislation of the Obama administration, such as the Affordable Care Act, the Dodd–Frank Act, and the American Recovery and Reinvestment Act of 2009. In 2013, under Reid's leadership, the Senate Democratic majority controversially invoked the "nuclear option" to eliminate the 60-vote requirement to end a filibuster for presidential nominations, other than nominations to the U.S. Supreme Court. Republicans took control of the Senate following the 2014 United States Senate elections, and Reid served as Senate Minority Leader from 2015 until his retirement in 2017. Reid is Nevada's longest-serving senator, surpassing John P. Jones's record by two days.

Reid was succeeded as the Senate Democratic leader by Chuck Schumer, whose leadership bid had been endorsed by Reid. Along with Alben W. Barkley and Mike Mansfield, Reid was one of only three senators to have served at least eight years as majority leader. Harry Reid International Airport, which serves the Las Vegas Valley, was named after Reid on December 14, 2021, two weeks before his death from cancer. The airport was previously named after Pat McCarran, one of Reid's Senate predecessors.

Harry Mason Reid Jr. was born on December 2, 1939, in Searchlight, Nevada, the third of four sons of Harry Reid, a rock miner, and Inez Orena (Jaynes) Reid, a laundress for local brothels. At that time, Searchlight was a small, impoverished town. His father died by suicide in 1972, at the age of 58, when Harry was 32 years old. His paternal grandmother was an English immigrant from Darlaston, Staffordshire. Reid's boyhood home was a shack with no indoor toilet, hot water or telephone.

Since Searchlight had no high school, Reid boarded with relatives 40 miles (64 km) away, in Henderson, so that he could attend Basic High School, where he played football and was an amateur boxer. While at Basic High, he met future Nevada governor Mike O'Callaghan, who was a teacher there and served as Reid's boxing coach. Reid attended Southern Utah University and graduated from Utah State University in 1961, where he double-majored in political science and history. He also minored in economics at Utah State's School of Commerce and Business Administration. He then attended George Washington University Law School while working as a police officer for the United States Capitol Police, and he earned his Juris Doctor in 1964.

Reid returned to Nevada after law school and served as Henderson city attorney before being elected to the Nevada Assembly for the multi-member fourth district of Clark County in 1968. In 1970, at age 30, Reid was chosen by O'Callaghan as his running mate for Lieutenant Governor of Nevada. Reid and O'Callaghan won their respective races, and Reid served as lieutenant governor from 1971 until 1974, when he ran for the U.S. Senate seat that was being vacated by Alan Bible. He lost by fewer than 700 votes to former governor Paul Laxalt. In 1975, Reid ran for mayor of Las Vegas and lost to Bill Briare.

Reid served as chairman of the Nevada Gaming Commission from 1977 to 1981. When Jack Gordon offered Reid a $12,000 bribe to get approval of new games for casinos, Reid brought in the FBI to tape Gordon's bribery attempt and arrest him. After FBI agents interrupted the transaction as prearranged, Reid lost his temper and attempted to choke Gordon, saying "You son of a bitch, you tried to bribe me!" before agents stopped him. Gordon was convicted in 1979 and sentenced to six months in prison. Reid presided over the 1979 hearing that refused to issue a gaming license to casino operator Frank Rosenthal because of his ties to organized crime groups such as the Chicago Outfit and particularly his close personal association with mobster Anthony Spilotro. Reid later stated that "Rosenthal was the only person that I was ever afraid of." Rosenthal loudly and publicly confronted Reid after the hearing, telling gathered reporters that he had performed many personal favors for Reid. Reid conceded under heated interrogation from Rosenthal that the two men had met for lunch at his Stardust Resort and Casino and that he had asked Rosenthal to cover up undesirable news stories. FBI wiretaps captured mobsters claiming that Reid was under their control, causing governor Robert List to feel pressure to ask Reid to resign. However, List believed Reid's assertions that the accusations were baseless. In 1981, Reid's wife found a bomb attached to the family station wagon; Reid suspected it was placed by Rosenthal or Gordon, although this has never been proven in court.