William Emmett Dever (born: March 13, 1862; died: September 3, 1929; buried in Calvary Cemetery) served as mayor of Chicago, Illinois, USA (1923-1927) for the Democratic Party.

Dever was born in Woburn, Massachusetts and entered his family's tanning business when he was fifteen. He left Woburn in 1882 and moved to Boston, where he was based while he traveled on tannery business for two years, during which time he met Kate Conway and they married. When Kate noticed an ad stating that tanners could make good money in Chicago, the couple moved west.

Upon arriving in Chicago in 1887, Dever got a job working at a tannery on Goose Island and he also began taking law courses at night at the Chicago College of Law . Upon graduation in 1890, he opened his own law practice. He ran for alderman in 1900, but was defeated. Two years later, he was elected alderman of the 17th Ward. In 1910, he was elected to his first term as a judge and was re-elected in 1916 and 1922.

In 1923, Democratic party boss George Brennan selected Dever as having the best chance of defeating incumbent mayor William Hale Thompson. Dever ran on a reform platform and Thompson withdrew from the race in favor of Arthur C. Leuder , who was easily defeated by Dever.

Dever's term in office saw many improvements to the city's infrastructure, including the completion of Wacker Drive, the extension of Ogden Avenue, the straightening of the Chicago River and the building of the city's first airport, Municipal Airport. He also fought against the corrupting influence of bootleggers and gangsters. Despite considering himself a wet, he enforced prohibition since it was the law of the land. The media labeled his war on bootleggers the Great Beer War and it resulted in a decline of crime.

By 1925, Chicago was in the middle of a gang war and many public officials were murdered. Dever tried to stem the violence and noted that although prohibition was a "tremendous mistake," he had no choice but to enforce it.

Dever ran for re-election in 1927 against "Big Bill" Thompson, who defeated him by 83,000 votes. Dever went on to serve as a vice-president of the Bank of America, but took a leave of absence and died of cancer in 1929.