Edward William Proxmire (November 11, 1915 – December 15, 2005) was an American politician. A member of the Democratic Party, he served as a United States Senator from Wisconsin from 1957 to 1989. He holds the record for being the longest-serving senator from Wisconsin.

Known as a political maverick and an aggressive critic of wasteful government spending, Proxmire invented and awarded the tongue-in-cheek Golden Fleece Award to appropriations he found particularly egregious. He was a member of the Senate Banking Committee, the Senate Appropriations Committee, and the Joint Economic Committee. On the Joint Economic Committee, he exposed numerous instances of wasteful spending on military programs such as the C-5 aircraft and the F-16 fighter, as well as other government programs such as the development of a supersonic transport airplane (SST).

The son of Dr. Theodore Stanley Proxmire, a Chicago-area surgeon, and Adele (Flanigan) Proxmire, Edward William Proxmire was born in Lake Forest, Illinois, on November 11, 1915. He later used "William" rather than "Edward" out of admiration for actor William S. Hart. He graduated from The Hill School (in Pottstown, Pennsylvania) in 1933, Yale University in 1938 (B.A.), Harvard Business School in 1940 (M.B.A.), and Harvard Graduate School of Public Administration in 1948 (M.P.A.). While at Yale, Proxmire joined the Chi Psi fraternity. During 1940 and 1941 Proxmire was a student clerk at J.P. Morgan & Co. and studied public speaking at Columbia University.

During World War II he joined the United States Army as a private, and advanced through the ranks to master sergeant. Proxmire later received a commission in the Military Intelligence branch. Most of his service involved counterintelligence work in the Chicago area, where members of his unit investigated individuals suspected of subversive activity. He served from 1941 to 1946, and was discharged as a first lieutenant. While in the Army, Proxmire also continued to study public speaking at Northwestern University. After discharge, he was an executive trainee at J. P. Morgan before returning to Harvard.

After getting his second master's degree while working as a teaching fellow at Harvard, Proxmire moved to Wisconsin to be a reporter for The Capital Times in Madison and to advance his political career in a favorable state. "They fired me after I'd been there seven months, for labor activities and impertinence," he once said. When he ran successfully for the state legislature in 1950, Proxmire was working as the business manager of the Union Labor News, a publication of the Madison Federation of Labor.

Proxmire served as a member of the Wisconsin State Assembly from 1951 to 1953. During his Assembly service, Proxmire was one of few members who maintained a perfect attendance record, a trait that he later continued in the U.S. Senate. While in the Assembly, he was employed as president of Artcraft Press of Waterloo. Proxmire was an unsuccessful candidate for Governor of Wisconsin in 1952, 1954 and 1956.

In August 1957, Proxmire won the special election to fill the remainder of the U.S. Senate term vacated by the May 2, 1957 death of Joseph McCarthy. After assuming his seat, Proxmire did not pay the customary tribute to his predecessor and stated instead that McCarthy was a "disgrace to Wisconsin, to the Senate, and to America."

Proxmire was reelected in 1958, 1964, 1970, 1976 and 1982; all but his 1964 win were by wide margins, including 71 percent of the vote in 1970, 73 percent in 1976 and 65 percent in 1982. In both of his last two campaigns, Proxmire refused contributions and spent less than $200 out of his own pocket, which covered the expenses related to filing re-election paperwork, and he mailed back unsolicited contributions. He was an early advocate of campaign finance reform. Throughout his Senate career, Proxmire also refused to accept reimbursements for travel expenses related to his official duties.