Robert Todd Lincoln was an American lawyer and businessman. The eldest son of President Abraham Lincoln and Mary Todd Lincoln, he was the only one of their four children to outlive his parents. Robert Lincoln became a business lawyer and company president, and served as both United States Secretary of War (1881–1885) and the U.S. ambassador to Great Britain (1889–1893).

Thomas "Tad" Lincoln was the fourth and youngest son of the 16th President of the United States Abraham Lincoln and his wife Mary Todd Lincoln.