Arnold Rothstein, American mob boss (b. 1882)
Arnold Rothstein (January 17, 1882 – November 6, 1928), nicknamed "The Brain", was an American racketeer, crime boss, businessman, and gambler in New York City. Rothstein was widely reputed to have organized corruption in professional athletics, including conspiring to fix the 1919 World Series. He was also a mentor of future crime bosses Lucky Luciano, Meyer Lansky, Frank Costello, and numerous others.

According to crime writer Leo Katcher, Rothstein "transformed organized crime from a thuggish activity by hoodlums into a big business, run like a corporation, with himself at the top". According to author Rich Cohen, Rothstein was the person who first realized that Prohibition was a business opportunity, a means to enormous wealth, who "understood the truths of early century capitalism (giving people what they want) and came to dominate them". His notoriety inspired several fictional characters based on his life, portrayed in contemporary and later short stories, novels, musicals, and films, including the character Meyer Wolfsheim in The Great Gatsby.Rothstein refused to pay a large debt resulting from a fixed poker game and was murdered in 1928. His illegal empire was broken up and distributed among a number of other underworld organizations and led in part to the downfall of Tammany Hall and the rise of reformer Fiorello La Guardia. Ten years after his death, his brother declared Rothstein's estate was insolvent.