Theodore Roosevelt, Jr. (October 27, 1858 – January 6, 1919), also known as T.R., and to the public (but never to friends and intimates) as Teddy, was the twenty-sixth President of the United States, and a leader of the Republican Party and of the Progressive Movement. He became President of the United States at the age of 42. He served in many roles including Governor of New York, historian, naturalist, explorer, author, and soldier. He is most famous for his personality: his energy, his vast range of interests and achievements, his model of masculinity, and his "cowboy" persona.