From Wikipedia:

Harriet Elisabeth Beecher Stowe (June 14, 1811 - July 1, 1896) was an American author and abolitionist.  She came from the religious Beecher family and became best known for her novel Uncle Tom's Cabin (1852), which depicts the harsh conditions experienced by enslaved African Americans.  The book reached an audience of millions as a novel and play, and became influential in the United States and in Great Britain, energizing anti-slavery forces in the American North, while provoking widespread anger in the South.  Stowe wrote 30 books, including novels, three travel memoirs, and collections of articles and letters.  She was influential both for her writings as well as for her public stances and debates on social issues of the day.