Paul Grattan Kirk Jr. (born January 18, 1938) is an American lawyer and politician who served as a United States Senator from Massachusetts from 2009 to 2010, having been appointed to fill the vacancy created by the death of Ted Kennedy.

He is the son of Josephine Elizabeth (née O'Connell) and Judge Paul G. Kirk Sr., an associate justice of the Supreme Judicial Court of Massachusetts.

[2] He is the chairman and chief executive officer of Kirk & Associates, Inc., a business advisory and consulting firm located in Boston.

He is also a member of the board of directors of the Hartford Financial Services Group, Inc., Rayonier, Incorporated, and Cedar Realty Trust, Inc.

Kirk resigned shortly after Republican vice president George H. W. Bush's victory over Massachusetts Governor Michael Dukakis in the 1988 presidential election.

On May 2, 2008, Paul Kirk formally pledged his superdelegate nomination vote in the summer 2008 national Democratic convention to Barack Obama.

Five years earlier in 2004, the Massachusetts General Court had withdrawn the authority of the governor to fill a U.S. Senate vacancy by appointment, to prevent the then-Governor Mitt Romney, a Republican, from appointing a fellow Republican to fill the remainder of Democrat John Kerry's Senate term, if Kerry were to win the 2004 presidential election.

[16][17][18][19][20] At that time, Senator Ted Kennedy successfully made personal appeals to Massachusetts Democratic legislative leaders to pass the bill, which had been stalled prior to his request.

Given the urgency of and narrow partisan support for some legislation before Congress, most notably health care reform, Democratic lawmakers and liberal pundits called for an interim senator to be appointed so that Massachusetts would have full Senate representation until the special election; Kennedy himself had requested such a change before he died.

[36] A Suffolk Superior Court judge dismissed the case the same day, and Kirk took the oath of office as senator that afternoon.

Kirk is a great-nephew of the late Cardinal William O'Connell and the brother-in-law of ice hockey player and coach Bill Cleary.