William Michael 'Billy' Bulger is a politician from Massachusetts in the United States. From 1978 until 1996, he served as President of the Massachusetts State Senate, one of the four most powerful positions in Massachusetts politics, along with the governor, speaker of the House, and mayor of Boston. Although a lifetime Democrat, in 1996 he was appointed President of the University of Massachusetts system by Republican governor William Weld.

Bulger is a consummate South Boston Irish American and a "triple eagle", graduating from Boston College high school, then Boston College as an undergraduate, then Boston College law school. He was elected to the Massachusetts House of Representatives in 1960 from South Boston, then to the Massachusetts State Senate in 1970.

His brother, Whitey Bulger, is the notorious leader of the 'Winter Hill gang', a Boston crime organization. For many years, Whitey Bulger was an FBI informant, while officially "on the lam" (i.e. officially he was on the run, aiming to evade capture). When the extent of the FBI's collaboration with Whitey became publicly known, this set off a large political scandal, and questions of Billy's possible secret knowledge of his brother's whereabouts have hounded him politically. He has been called to testify before the United States House of Representatives before a committee investigating the FBI's behavior in his brother's case.

In the year 2002, Republican Mitt Romney was elected governor of Massachusetts on an anti-corruption platform, and he immediately set out on a campaign to eliminate Bulger's position as President of the UMass system. Romney was later joined in this campaign by many Democrats, although this was a very divisive issue in Massachusetts politics. On August 6, 2003, Bulger announced that he would resign as President of the system.