Answer:
Louis XIV (the 14th)
Step-by-step explanation:
He got on the throne at age of 5, at the death of his father (Louis XIII).
His reign lasted 72 years... more than any other King of France and one of the longest in history of the world. He was nicknamed Le Roi Soleil (the Sun King), because of its longevity.
Elizabeth II of England has now done over 67 years, to give you a reference point.