Stephen Symonds Foster (November 17, 1809 – September 13, 1881) was a radical American abolitionist known for his dramatic and aggressive style of public speaking, and for his stance against those in the church who failed to fight slavery. His marriage to Abby Kelley brought his energetic activism to bear on women's rights. He spoke out for temperance, and agitated against any government, including his own, that would condone slavery.