John Bayard Anderson (February 15, 1922 – December 3, 2017) was an American lawyer and politician who served in the United States House of Representatives, representing Illinois's 16th congressional district from 1961 to 1981. A member of the Republican Party, he also served as the Chairman of the House Republican Conference from 1969 until 1979. In 1980, he ran an independent campaign for president, receiving 6.6% of the popular vote.

Born in Rockford, Illinois, Anderson practiced law after serving in the Army during World War II. After a stint in the United States Foreign Service, he won election as the State's Attorney for Winnebago County, Illinois. He won election to the House of Representatives in 1960 in a strongly Republican district. Initially one of the most conservative members of the House, Anderson's views moderated during the 1960s, particularly regarding social issues. He became chairman of the House Republican Conference in 1969 and remained in that position until 1979. He strongly criticized the Vietnam War as well as President Richard Nixon's actions during the Watergate scandal.

Anderson entered the 1980 Republican presidential primaries, introducing his signature campaign proposal of raising the gas tax while cutting Social Security taxes. Anderson established himself as a contender for the nomination in the early primaries but eventually dropped out of the Republican race, choosing to pursue an independent campaign for president. In the election, he finished third behind Republican nominee Ronald Reagan and Democratic President Jimmy Carter. He won support among Democrats who became disillusioned with Carter, as well as Rockefeller Republicans, independents, liberal intellectuals, and college students.

After the 1980 election, he resumed his legal career and helped found FairVote, an organization that advocates electoral reform, including an instant-runoff voting system. He also won a lawsuit against the state of Ohio, Anderson v. Celebrezze, in which the Supreme Court struck down early filing deadlines for independent candidates. Anderson served as a visiting professor at numerous universities and was on the boards of several organizations. He died at the age of 95.

Anderson was born in Rockford, Illinois, where he grew up, the son of Mabel Edna (née Ring) and Ernest Albin Anderson. His father was a Swedish immigrant, as were his maternal grandparents. His father was born in 1885 in Eriksberg parish, Västergötland. His mother was born in 1886 Stillman Valley, Illinois, her father had immigrated from Rydaholm parish, Småland.

In his youth, he worked in his family's grocery store. He graduated as the valedictorian of his class (1939) at Rockford Central High School. He graduated from the University of Illinois at Urbana–Champaign in 1942, and started law school; his education was interrupted by World War II. He enlisted in the Army in 1943, and served as a staff sergeant in the U.S. Field Artillery in France and Germany until the end of the war, receiving four service stars. After the war, Anderson returned to complete his education, earning a Juris Doctor (J.D.) from the University of Illinois College of Law in 1946.

Anderson was admitted to the Illinois bar the same year, and practiced law in Rockford. Soon after, he moved east to attend Harvard Law School, obtaining a Master of Laws (LL.M.) in 1949. While at Harvard, he served on the faculty of Northeastern University School of Law in Boston. In another brief return to Rockford, Anderson practiced at the law firm Large, Reno & Zahm (now Reno & Zahm LLP). Thereafter, Anderson joined the Foreign Service. From 1952 to 1955, he served in Berlin, as the Economic Reporting Officer in the Eastern Affairs Division, as an adviser on the staff of the United States High Commissioner for Germany. At the end of his tour, he left the foreign service and once again returned to the practice of law in Rockford.

Soon after his return, Anderson was approached about running for public office. In 1956, Anderson was elected State's Attorney in Winnebago County, Illinois, first winning a four-person race in the April primary by 1,330 votes and then the general election in November by 11,456 votes. After serving for one term, he was ready to leave that office when the local congressman, 28-year incumbent Leo E. Allen, announced his retirement. Anderson joined the Republican primary for Allen's 16th District seat—the real contest in this then-solidly Republican district based in Rockford and stretching across the state's northwest corner. He won a five-way primary in April (by 5,900 votes) in April and then the general election in November (by 45,000 votes). He served in the United States House of Representatives for ten terms, from 1961 to 1981.