William Martin Dickson, also known as William M. Dickson (1827-1889), was a lawyer, prosecuting attorney, and judge from Cincinnati, Ohio, United States. He was one of the founders of the Republican Party and assisted in the framing of the Emancipation Proclamation. Alphonso Taft, the father of President and Chief Justice William Howard Taft, and Thomas Marshall Key were his law partners. A relative by marriage, Dickson was a presidential elector supporting Lincoln during the 1860 election. His wife, Annie Maria Palmer was the first cousin of Mary Todd Lincoln.