William Dillwyn

William Dillwyn
portrait by Charles Leslie
Bornc. 1743 
Died28 September 1824  (aged 80–81)
Spouse(s)Sarah Logan Smith, Sarah Weston 
Children9, including Lewis Weston Dillwyn

William Dillwyn (1743, Philadelphia – 28 September 1824) was a British American-born Quaker of Welsh descent, active in the abolitionist movement in colonial America and after 1774, Great Britain. He was one of the twelve committee members of the Society for Effecting the Abolition of the Slave Trade when it was formed in 1787.

William was the son of John Dillwyn and Susanna Painter. He attended the Friends' English School of Philadelphia where he was taught by Anthony Benezet. His elder brother was George Dillwyn (1738-1820), the Quaker minister.