Theodore Roosevelt, bynames Teddy Roosevelt and TR, (born October 27, 1858, New York, New York, U.S.—died January 6, 1919, Oyster Bay, New York), 26th president of the United States (1901–09) and a writer, naturalist, and soldier. He expanded the powers of the presidency and of the federal government in support of the public interest in conflicts between big business and labour and steered the nation toward an active role in world politics, particularly in Europe and Asia.