Theodore "Teddy" Roosevelt (October 27, 1858 – January 6, 1919) was the 26th President of the United States.
Strictly speaking, President Theodore Roosevelt was Theodore Roosevelt, Jr., but since he so eclipsed his father in fame, the father is usually known as Theodore Roosevelt, Sr., and Theodore Roosevelt, Jr., is used for the President's oldest son. The President's grandson is known as Theodore Roosevelt III, etc.