William Marcy Tweed (1823-1878), commonly known as Boss Tweed, led Tammany Hall, New York City's notorious Democratic political machine. During the 1860s and '70s, Tweed and his Tammany associates—the so-called "Tweed Ring"—stole millions of dollars from the city treasury through theft and extortion. Historians have estimated that Tammany Hall pilfered between $20 million and $200 million from New York taxpayers.
Tweed was elected to serve as a New York City alderman in 1851. He ascended the ranks of the municipal government and then served one term in Congress, but quickly found that power and (stolen) wealth were easier to acquire and maintain at the local level. By 1868, Tweed controlled the entire Democratic Party in the state of New York, but lost control in 1871 when a slate of opposition candidates successfully ran against his Tammany officials. Two years later, he was convicted of forgery and larceny, but only served two years in prison. He was immediately re-arrested when New York State sued him for $6 million. Tweed managed to escape from debtor's prison and flee to Cuba, but the State Department tracked him to Spain, where he was captured. Tweed was extradited to New York and died in debtor's prison on 12 April 1878.