As of 2015, there have been 44 presidents of the United States. As Grover Cleveland held the office in two non-sequential terms, only 43 unique persons have held the position of president.
The first president of the United States was George Washington; Washington served in office from 1789 to 1797. Of the men who have served as president, 21 of them won re-election, including 13 who served two full terms. Four men assumed the office from their predecessor and later won election to a full term on their own right. Four presidents were assassinated while in office, while six presidents survived assassination attempts. Additionally, four other presidents died of illness while in office.