Harry Robbins Haldeman (October 27, 1926 – November 12, 1993) was an American political aide and businessman, best known for his service as White House Chief of Staff to President Richard Nixon and his consequent involvement in the Watergate scandal.

Born in California, Haldeman served in the Navy Reserves in World War II and attended UCLA. In 1949, he joined the J. Walter Thompson advertising agency, where he worked for 20 years as a prominent advertising executive in both Los Angeles and New York City. He made a name for himself early in Los Angeles social circles from his work as chairman of the UCLA Alumni Association and a member of the University of California Board of Regents.

A long family association with the Republican Party and his own interest drew Haldeman to politics. In the 1950s, he became acquainted with Nixon, for whom he developed both an intense respect and steadfast loyalty. He began as an advance man on President Dwight D. Eisenhower's reelection campaign in 1956, again worked as an advance man on Nixon's 1960 presidential campaign, and managed Nixon's 1962 run for governor of California. When Nixon was elected President in 1968, he selected Haldeman as his chief of staff.

Haldeman is credited with implementing more significant changes to White House staffing systems and Executive Branch governance and operations than any chief of staff before him or since, and it is the "Haldeman system" that presidential administrations continue to operate on today. His intensity and no-nonsense management style earned him a reputation as a stern taskmaster who expected top-notch performance.

After he left the Nixon administration in April 1973, Haldeman was tried on counts of perjury, conspiracy, and obstruction of justice for his role in the Watergate cover-up. He was found guilty and imprisoned for 18 months. Upon Haldeman's release, he returned to private life and was a successful businessman and real estate developer until his death from cancer in 1993 at the age of 67.