Hypatia 370?-415 The first woman mathematician about whom we have any biographical knowledge and knowledge of her work.
Sonia Kovalevsky 1850-1891 The first woman to receive a doctorate in mathematics (in 1874 at the University of Gottingen).
Winifred Edgerton Merrill 1862-1951 The first woman to receive a doctorate in mathematics in the U.S. (in 1886 at Columbia University).
Evelyn Boyd Granville 1924- One of the 1st 2 African-American women to receive a doctorate in mathematics (in 1949 at Yale University).
Cathleen S. Morawetz 1923-Many firsts, including the first woman mathematician to win a National Medal of Science (in 1998).
Karen K. Uhlenbeck 1942- Many firsts, including the first of two women to receive a MacArthur Fellowship (in 1982), and the 2nd woman to speak at ICM (in 1990)
Ingrid Daubechies 1954- The first woman mathematician to become a full professor at Princeton University (1993).
Katherine Okikiolu 1965- The first person of African descent to win a Sloan Research Fellowship in mathematics. She also won the Presidential Early Career Award for Scientists and Engineers. (in 1997)
Melanie Wood 1981- First woman U.S. math olympiad team member - tied for first-place spot. (1998) She won a silver medalist in the world competition.