William Richardson (1656–1727) was an Irish politician. He was the son of Major Edward Richardson of Legacorry (aka Richhill Castle), County Armagh, MP for County Armagh and his wife Anne Sacheverell, daughter of Francis Sacheverell and Dorothy Blennerhassett. He was educated at Trinity College, Dublin. He was appointed High Sheriff of Armagh for 1690 and elected the MP for Armagh in 1692 and 1715 and for Hillsborough in 1703.