Richard Green Lugar (/ˈluɡər/ LOO-gər; April 4, 1932 – April 28, 2019) was an American politician who served as a United States senator from Indiana from 1977 to 2013. He was a member of the Republican Party.

Born in Indianapolis, Lugar graduated from Denison University and the University of Oxford. He served on the Indianapolis Board of School Commissioners from 1964 to 1967 before he was elected to two terms as mayor of Indianapolis, serving from 1968 to 1976. During his tenure as mayor, Lugar served as the president of the National League of Cities in 1971 and gave the keynote address at the 1972 Republican National Convention.

In 1974, Lugar ran his first campaign for the U.S. Senate. In the year's senate elections he lost to incumbent Democratic Senator Birch Bayh. He ran again in 1976, defeating Democratic incumbent Vance Hartke. Lugar continued to be reelected until 2012, when he was defeated by Indiana State Treasurer Richard Mourdock in the Republican primary by 21 points, who subsequently lost in the general election to Democrat Joe Donnelly, ending his 36-year tenure in the U.S. Senate. Lugar ran for the Republican nomination for president of the United States in the 1996 primaries but lack of success led to his withdrawal early in the campaign.

During Lugar's tenure, he served as Chairman of the Senate Committee on Foreign Relations from 1985 to 1987 and from 2003 to 2007, serving as the ranking member of the committee from 2007 until his departure in 2013. Lugar also twice served as Chairman of the Senate Committee on Agriculture, Nutrition and Forestry, from 1995 to 2001 and briefly again in part of 2001. Much of Lugar's work in the Senate was toward the dismantling of nuclear, biological, and chemical weapons around the world, co-sponsoring his most notable piece of legislation with Georgia Democrat Sam Nunn: the Nunn–Lugar Act.

Following his service in the Senate, Lugar created a nonprofit organization which specializes in the policy areas he pursued while in office.

Richard Lugar was born on April 4, 1932, in Indianapolis, Indiana, the son of Bertha (née Green) and Marvin Lugar. He was of part German descent. Lugar attended Shortridge High School. During this time he attained the rank of Eagle Scout, the Boy Scouts' highest. Later, he became a recipient of the Distinguished Eagle Scout Award from the Boy Scouts of America. He graduated first in his class at Shortridge High School in 1950 and from Denison University in 1954, where he was a member of Beta Theta Pi. He went on to attend Pembroke College, Oxford, England, as a Rhodes Scholar and received a second bachelor's degree and a master's degree in 1956. At Oxford, Lugar was a member of the Oxford University men's basketball team that won the 1955 A.B.B.A. National Championship. He served in the United States Navy from 1956 to 1960; one of his assignments was as an intelligence briefer for Admiral Arleigh Burke. He achieved the rank of Lieutenant, Junior Grade.

Lugar managed his family's 604-acre (244 ha) Marion County corn, soybean and tree farm. Before entering public life, he helped his brother Tom manage the family's food machinery manufacturing business in Indianapolis.

Lugar served on the Indianapolis Board of School Commissioners from 1964 to 1967. He was elected mayor of Indianapolis in 1967, at the age of 35, defeating incumbent Democrat John J. Barton, and began serving the first of two mayoral terms in 1968. (A political cartoon of the time questioned how an Eagle Scout could survive in the world of politics.) He was closely associated with the adoption of Unigov in 1970, which unified the governments of Indianapolis and Marion County. The Unigov plan helped trigger Indianapolis's economic growth and earned Lugar the post of president of the National League of Cities in 1971. In 1972, Lugar was the keynote speaker at the Republican National Convention. During this time he became known as "Richard Nixon's favorite mayor", owing to his support for devolving federal powers to local communities. When Nixon visited Indianapolis in February 1970, he stated during a speech that he would meet with Lugar and other mayors ahead of a conference with Governors on environmental issues. On March 14, 1974, Lugar dismissed Police Chief Winston L. Churchill following allegations of widespread corruption in the Indianapolis Police Department. Lugar stated the dismissal came following meetings with dozens of policemen and after having had the counsel of a seven-member committee of citizens to aid in the investigation.