Elizabeth "Mumbet" Freeman
Born into slavery in 1742, Mumbet (as she was then known) became the first woman to sue successfully for her freedom in the American Republic.  She was working for her master, Colonel John Ashley, in Sheffield, Massachusetts when she heard people discussing the new Massachusetts Constitution and its Declaration of Rights.  She then approached attorney Theodore Sedgwick to bring a case in the Court of Common Pleas, arguing that she too had rights under this constitution.  The name of her fellow slave, Brom, was added to the case,  Brom and Bett v. Ashley, which in 1781, succeeded in winning them their freedom.  Afterwards, John Ashley asked her to return to his home as a paid employee, but instead she worked as a housekeeper and nurse for the Sedgwicks under her new name, Elizabeth Freeman.  She died in 1829 and was buried in the Sedgwick family plot. 
>> Learn more: http://www.massmoments.org/moment.cfm?mid=244