Maria W. Stewart (née Miller) (1803 – December 17, 1879) was an American teacher, journalist, abolitionist and lecturer known for her role in the anti-slavery and women's rights movements in the United States. The first known American woman to speak to a mixed audience of men and women, white and black, she was also the first African American woman to make public lectures, as well as to lecture about women's rights and make a public anti-slavery speech.

The Liberator published two pamphlets by Stewart: Religion and the Pure Principles of Morality, The Sure Foundation on Which We Must Build (which called for abolition and Black autonomy) in 1831, and another of religious meditations, Meditations from the Pen of Mrs. Maria Stewart (1832). In February 1833, she addressed Boston's African Masonic Lodge, which soon ended her brief lecturing career.

Her claim that black men lacked "ambition and requisite courage" caused an uproar among the audience, and Stewart decided to retire from giving lectures. Seven months later, she gave a farewell address at a schoolroom in the African Meeting House ("Paul's Church"). After this, she moved to New York City, then to Baltimore, and finally Washington, D.C., where she worked as a schoolteacher, and then head matron at Freedmen's Hospital, where she eventually died.