Benjamin "Bugsy" Siegel (/ˈsiːɡəl/; February 28, 1906 – June 20, 1947) was a Jewish-American mobster who was a driving force behind the development of the Las Vegas Strip. Siegel was influential within the Jewish Mob, along with his childhood friend and fellow gangster Meyer Lansky, the Italian-American Mafia, and the largely Italian-Jewish National Crime Syndicate. Described as "handsome" and "charismatic," Siegel became one of the first front-page celebrity gangsters.

Siegel was one of the founders and leaders of Murder, Inc. and became a bootlegger during American Prohibition. After the Twenty-first Amendment was passed in 1933 repealing Prohibition, he turned to illegal gambling. In 1936, Siegel left New York and moved to California. His time as a mobster during this period was mainly as a hitman and muscle, as he was noted for his prowess with guns and violence. In 1941, Siegel was tried for the murder of friend and fellow mobster Harry Greenberg, who had turned informant; he was acquitted in 1942.

Siegel traveled to Las Vegas, Nevada, where he handled and financed some of the city's original casinos. He assisted developer William R. Wilkerson's Flamingo Hotel after Wilkerson ran out of funds. Siegel assumed control of the project and managed the final stages of construction. The Flamingo opened on December 26, 1946, in a three-day event that was well received. Without a hotel to accompany the casino, the Flamingo struggled and closed from February 6 until the hotel reopened March 1, 1947. Siegel’s mob partners were convinced that an estimated US$1 million of the construction budget overrun had been skimmed by Siegel, his girlfriend Virginia Hill or by both of them. On June 20, 1947, Siegel was shot dead at the age of 41 by a sniper through the window of Hill's Linden Drive mansion in Beverly Hills, California.

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