The Bull Moose
A former governor, rough rider, New York City police commissioner and cowboy, Theodore Roosevelt was only 42 years old when he assumed the presidency in 1901 due to the McKinley assassination. T.R. was and remains the youngest person to ever hold the high office, and his administration marked a radical change for his country thanks to his seemingly superhuman levels of stamina.
A Roosevelt By Any Other Name
After retiring from the presidency, Theodore Roosevelt preferred to be addressed as "Colonel Roosevelt," or simply "The Colonel." This took President Taft some getting used to since he enjoyed calling his friend "Mr. President" - much to Theodore Roosevelt and Nellie Taft's irritation.
T.R. had a problem keeping a low profile after his presidency, and it was mostly due to himself. According to his daughter Alice, her father "wanted to be the bride at every wedding and the corpse at every funeral." And, just as likely, the president of every white house he passed.