William Maurice Cowan (born April 4, 1969) is an American politician who served as a United States Senator from Massachusetts from February 1, 2013, to July 15, 2013.

A member of the Democratic Party, he previously served as legal counsel and chief of staff to Governor Deval Patrick.

Patrick appointed him on an interim basis to fill the vacancy left by fellow Democrat John Kerry, who resigned to become U.S. Secretary of State.

[1] Cowan declined to run in the 2013 special election to complete the remainder of Kerry's term.

[2] Cowan was born on April 4, 1969, in rural Yadkinville, North Carolina, the son of a machinist and a seamstress.

His assignments in Northeastern's cooperative program, which provides students with work experience as part of its educational program, included stints in the office of a state trial court, at North Carolina Prison Legal Services, and with the Palm Beach County Public Defender's Office.

[6] As Patrick's counsel, Cowan was responsible for the legal operations of the executive branch and oversaw the governor's judicial nominations, including that of Chief Justice of the Supreme Judicial Court Roderick L. Ireland.

His principal projects as staff included legislation to contain the growth of health care costs and to expand gaming, as well as investigating and reorganizing the state Parole Board.

[7] He received an honorary degree from Georgetown University in 2013 and spoke at the commencement ceremony for the McDonough School of Business.