William Maurice “Mo” Cowan (born April 4, 1969) is an American politician and lawyer who served as a United States Senator from Massachusetts from February 1, 2013 to July 16, 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.
He declined to run in the 2013 special election to complete the remainder of Kerry's term.
He was succeeded by fellow Democrat Ed Markey.
Cowan was the eighth African-American U.S.
Senator and the second from Massachusetts after Edward Brooke.
He was one of three African-American U.S.
Senators in the 113th Congress, along with Republican Senator Tim Scott from South Carolina and Democrat Cory Booker from New Jersey, although he did not serve alongside Booker, who took office on October 31, 2013.