Barbara Ann Williams is an American radio astronomer who was the first African-American woman to earn a PhD in astronomy (University of Maryland, College Park, 1981). Her research largely focused on compact galaxy groups, in particular observations of their emissions in the H I region in order to build up a larger scale picture of the structure and evolution of galaxies. Williams was named as the Outstanding Young Woman of America in 1986. She is a retired associate professor in the Department of Physics and Astronomy at the University of Delaware.

Williams earned her bachelor's degree in physics at the University of North Carolina at Greensboro.^[1] She moved to the University of Maryland, College Park for her graduate studies, earning a Master's and PhD in the field of radio astronomy in 1981.^[2][3] She was a member of Phi Beta Kappa academic honor society. Williams was the first African-American woman to earn a PhD in astronomy.^[1] She studied elliptical galaxies using HI emissions.^[4] She returned to the University of North Carolina at Greensboro as a research associate, where she worked until 1984. In 1984 Williams was appointed as a postdoctoral fellow at the University of North Carolina at Chapel Hill. She spent a year as a NASA-American Society for Engineering Education summer faculty member at the Goddard Space Flight Center.^[5] She was named as the 1986 Outstanding Young Woman of America.^[5]

Williams's research focused on radio astronomy and the study of galaxies.^[6][7] She used radio waves to examine groups of galaxies with compact cores^{[8][9][10][11]} and HI emissions to study several galaxies, including the IC 698 group.^[12][13] Williams's work on the Hickson Compact Group of galaxies established that atomic gases must undergo a phase transformation to result in the observed HI deficiency.^[14] She used VLA neutral hydrogen imaging of compact galaxy groups.^[15][16]

Williams was made an associate professor at the University of Delaware in 1986.^[1] There, Williams later studied educational research^[17] and in particular strategies to retain women in physics.^[18] Williams is a Fellow of the National Society of Black Physicists.^[19]

Along with Sheella Mierson, Williams was the co-principal investigator of a study on problem-based learning in introductory sciences, in the Center for Teaching Effectiveness, University of Delaware.^[20]

• Profile on Astronomers of the African Diaspora