Léopold III Augustin (27th November 1692 - 12th February 1717) was a monarch of the House of Lorraine who ruled as King of Lorraine and Burgundy from the death of his father, Charles III, in 1713 until his own mysterious death in 1717. He was the only son of King Charles III and his second wife, Claudine Louise de Guise, making him the younger half-brother of his successor, Elisabeth I. Léopold, as the only son of his father, was always expected to inherit the throne and further the line. He did come to the throne, despite the dislike of this by the Habsburg monarchy due to the passing over of the Princess Elisabeth (whose deceased mother was a Habsburg). Léopold was an unpopular king, generally considered haughty, inefficient and indulgent. His unexplained death in February 1717 led to the ascension of Elisabeth as Queen.
Léopold was best known for his incompetence as a ruler, as well as his massive indulgence and spending which led to the economic downturn felt by his kingdom for decades to come. Léopold was disliked by many nobles and peasants alike for his misrule, as well as his tyrannical actions against the nobility. He often seized the wealth of noble houses to feed his own habits, much to their disdain. This all perhaps contributed to his mysterious and unexplained death in 1717. Léopold vanished on 12th February 1717 and was declared dead after two weeks of searching. His body was found on March 4th 1717, in a shallow part of the Meurthe River. His death is rumoured to have been a murder, though no concrete answer has presented itself as to how the King came to die.