President of Argentina
Under the 1994 constitutional amendment, the President serves for four years, with a possibility of immediate reelection for one more term. However, unlike the President of the United States, in Argentina, a person may be reelected again after serving for two terms and staying out of office for the following term. So after serving for two consecutive periods, the president is not allowed to run for a third consecutive one, but may return for the two following elections and so on. There is no limit for a person to be a candidate if he or she does not win the elections.
Presidency of Franklin D. Roosevelt
Franklin Delano Roosevelt served as President from March 1933 to April 1945, the longest tenure in American history. He may have done more during those twelve years to change American society and politics than any of his predecessors in the White House, save Abraham Lincoln. Of course, some of this was the product of circumstances; the Great Depression and the rise of Germany and Japan were beyond FDR's control. But his responses to the challenges he faced made him a defining figure in American history.