Theodore Roosevelt was a leader.
Theodore Roosevelt Jr. ( [ ˈroʊzəvɛlt ] ; October 27 , 1858 -- January 6 , 1919 ) was an American statesman , author , explorer , soldier , naturalist , and reformer who served as the 26th President of the United States from 1901 to 1909 . In polls of historians and political scientists , Roosevelt is generally ranked as one of the five best presidents . United States presidential election, 1904 . Incumbent President and Republican candidate Theodore Roosevelt , having succeeded to the presidency upon the assassination of William McKinley in September 1901 , was elected to a term in his own right .