Twenty-second Amendment to the United States Constitution
Since coming into force in 1951, the amendment has applied to six presidents who have been elected twice: Dwight D. Eisenhower, Richard Nixon, Ronald Reagan, Bill Clinton, George W. Bush, and Barack Obama. It has also applied to two who entered office intra-term due to their predecessor's death or resignation: Lyndon B. Johnson and Gerald Ford. Johnson became president in November 1963, following the assassination of John F. Kennedy, served out the final of Kennedy's term, and was elected to a full four-year term in 1964. Four years later, he briefly ran for a second full term, but withdrew from the race during the party primaries. Had Johnson served a second full term – through January 20, 1973 – the total length of his presidency would have been ; as it happened, Johnson died two days after this date. Gerald Ford, who became president in August 1974 following the resignation of Richard Nixon, served the final of Nixon's term, and attempted to win a full four-year term in 1976, but was defeated by Jimmy Carter. Johnson was eligible to be elected to two full terms in his own right, as he had served less than two years of Kennedy's unexpired term, whereas Ford was eligible to be elected to only one full term, as he had served more than two years of Nixon's unexpired term.
President of the Philippines
Article 7, Section 2 of the Constitution reads:
"No person may be elected President unless he is a natural-born citizen of the Philippines, a registered voter, able to read and write, at least forty years of age on the day of the election, and a resident of the Philippines for at least ten years immediately preceding such election." 
The Constitution also provides term limits where the President is ineligible for reelection and a person who has succeeded as President and has served as such for more than four years will be ineligible to be elected for a second term. However, with the case of Joseph Estrada who was elected president in 1998, deposed in 2001, and again ran for the presidency in 2010, the Constitution's wording where "[the] President shall not be eligible for any re-election" remains unclear as his case was never brought to the Supreme Court. It remains unclear whether the term limit of no re-election applies only to the incumbent President or for any person who has been elected as President.