Sidney Richard Yates (August 27, 1909 – October 5, 2000) was an American attorney and Democratic Party politician who represented the state of Illinois in the United States House of Representatives for twenty-four terms from 1949 to 1963 and 1965 to 1999, one of the longest tenures in the history of the House. He was an advocate for liberal causes and a long-time member of the House Appropriations Committee, where he became known for staunch U.S. support of Israel, and federal funding for parks, historical conservation, and the arts.

A native of Chicago, he graduated from Lake View High School in 1928. He received bachelor's (1931) and J.D. (1933) degrees from the University of Chicago, was admitted to the bar, and practiced law in Chicago. In addition to working as an attorney, Yates also played semiprofessional basketball in the 1930s. He gained his initial experience in government as an attorney for the state bank receiver (1935–1937), and an assistant state attorney general specializing in traction railroads for the Illinois Commerce Commission (1937–1940). During World War II, Yates served in the United States Navy for two years (1944–1946) as an attorney based in Washington, D.C.

In 1948, Yates was elected to Congress, and he served from 1949 to 1963. After an unsuccessful run against Everett Dirksen for the United States Senate in 1962, in 1964 Yates was again elected to the House. He served from 1965 to 1999, and did not run for reelection in 1998. He was a longtime member of the House Appropriations Committee, where he became known for staunch U.S. support of Israel, and federal funding for parks, historical conservation, and the arts. Yates was also an advocate for several liberal causes, including opposition to discrimination based on age. At the time he concluded his service, he was the third oldest person to ever serve in the House (age 89) behind Charles Manly Stedman and Isaac R. Sherwood, and one of the longest-tenured members in the history of Congress (total House service of 48 years).

Yates died in Washington in 2000. He was buried at Memorial Park Cemetery in Skokie, Illinois.

Yates was born in Chicago, Illinois, the youngest of six children of Lithuanian Jewish immigrants Louis and Ida Yates. He grew up in Chicago and was an office boy at Variety's Chicago office during the 1920s. He graduated from the University of Chicago in 1931 with a Bachelor of Philosophy degree and received a J.D. degree from the University of Chicago Law School in 1933. While in college, Yates joined the Pi Lambda Phi fraternity. He also played basketball, and was selected for All Big Ten honors. In the mid-1930s, he played semiprofessional basketball and practiced law. Yates was an attorney for the Illinois state bank receiver from 1935 to 1937. From 1937 to 1940 he was an assistant state attorney general attached to the Illinois Commerce Commission as a traction attorney. He served in the United States Navy during World War II, assigned as an attorney for the Bureau of Ships in Washington, DC.

From 1949 to 1963 and 1965 to 1999, Yates served in the House of Representatives as a Democrat. Although the boundaries of his district changed over the years, it was always anchored in the Chicago lakefront. From the 1970s onward, Chicago's declining population resulted in the district spilling into the northern suburbs. By the time Yates retired, his district also included Evanston, Des Plaines, Glenview, Rosemont and Skokie.

Yates was one of the first congressmen to speak out against age discrimination, arguing in 1951 that mandatory retirement of workers was wrong and deprived older people of their right to lead a proud, productive and independent life.^{[citation needed]}

During the late 1950s, after a series of lurid magazine articles and Hollywood films helped to sensationalize youth gangs and violence, Yates called for legislation to ban automatic-opening or switchblade knives, melodramatically proclaiming that "Vicious fantasies of omnipotence, idolatry...barbaric and sadistic atrocities, and monstrous violations of accepted values spring from the cult of the weapon, and the switchblade knife is included in this. Minus switchblade knives and the distorted feeling of power they beget—power that is swaggering, reckless, and itching to express itself in violence—our delinquent adolescents would be shorn of one of their most potent means of incitement to crime." The ban on switchblade knives was eventually enacted into law as the Switchblade Knife Act of 1958. Rep. Yates and other congressmen supporting the Switchblade Knife Act believed that by stopping the importation and interstate sales of automatic knives (effectively halting sales of new switchblades), the law would reduce youth gang violence by blocking access to what had become a symbolic weapon. However, while switchblade imports, domestic production, and sales to lawful owners soon ended, later legislative research demonstrated that youth gang violence rates had in fact rapidly increased, as gang members began using firearms instead of knives.