Frederick Aiken was an American lawyer and politician born in 1826. He is best known for his role as the defense attorney for Mary Surratt, the first woman executed by the United States federal government. Aiken's defense of Surratt during the Lincoln assassination trial was controversial and highlighted the tensions of the post-Civil War era. Aiken served as a captain in the Union Army during the Civil War and later became a prominent figure in Washington, D.C. He was also involved in local politics and served as a member of the District of Columbia Board of Commissioners. Aiken passed away in 1878.