Harry Herbert Frazee (June 29, 1880 – June 4, 1929) was an American theatrical agent, producer, and director, and owner of Major League Baseball's Boston Red Sox from 1916 to 1923. He is well known for selling Babe Ruth to the New York Yankees, which started the alleged Curse of the Bambino.

Harry Frazee was born June 29, 1880, in Peoria, Illinois, son of William and Margaret Frazee. He attended Peoria High School, where he was a baseball teammate of Harry Bay, who later played for Major League Baseball teams in Cincinnati and Cleveland. At 16, Frazee became assistant manager of the Peoria Theater. Within a year, he was player-coach of the Peoria Distillers semi-pro baseball club. As his theatrical endeavors continued, Frazee moved to Chicago, where he built the Cort Theater in 1907.

After several successful shows, Frazee went to New York City, where in 1913 he built the Longacre Theatre on West 48th Street and staged hit plays such as Fine Feathers by Eugene Walter and the musical Adele. He also promoted a boxing match between Jess Willard and Jack Johnson on April 5, 1915 in Havana, Cuba and was reported by then to be a millionaire.

Frazee was a Freemason.

Frazee bought the Boston Red Sox baseball team from Joseph Lannin for a reported $675,000 after their victory in the 1916 World Series. The Sox won another World Series title in 1918. The team finished sixth in 1919, and after that season Frazee started selling players to the New York Yankees, most notoriously Babe Ruth. He then left the Red Sox in bankruptcy while continuing to produce theatre shows. After the sale of Ruth, the team crashed into the American League cellar and did not finish above .500 until 1934. The Red Sox did not win another pennant until 1946, and did not win another World Series until 2004. The 86-year World Series drought is the third-longest in MLB history, trailing only the Chicago Cubs (108 years from 1908 to 2016) and Chicago White Sox (88 years from 1917 to 2005).

Frazee backed a number of New York theatrical productions (before and after Ruth's sale), the best-known of which is probably No, No, Nanette, which was once claimed, and later debunked, as the specific play that Ruth's sale financed (it was actually what paid off the Fenway Park mortgage that the Ruth sale included). He was the subject of an unflattering portrait in Fred Lieb's account of the Red Sox, which further insinuated that he had sold Ruth to finance a Broadway musical. This became a central element in the Curse of the Bambino.

The truth is more nuanced and has as much to do with a long-running dispute between Frazee and American League founder and president Ban Johnson as it does with Frazee's finances. Frazee was the first American League owner who Johnson had not essentially hand-picked, and was unwilling to simply do Johnson's bidding. Although they seemed to settle their differences when Frazee hired Ed Barrow, a friend of Johnson's, as manager, their relationship worsened again when Frazee loudly criticized Johnson's handling of the issues brought about by the United States entering World War I. For his part, Johnson was angered by the open presence of gamblers and bookies at Fenway Park. These factors led Johnson to actively seek to push Frazee out.

Additionally, Frazee's theater ventures didn't generate even a fraction of the capital needed to meet the Red Sox' expenses. He often found himself having to borrow from the Red Sox to meet his other commitments.