King Louis XVI (16th) ruled France 1774 to his death…

.. by guillotine in the Reign of Terror preceding the French Revolution in 1793.  His reign began with the attempt to bring about “The Age of Enlightenment”, which included the elimination of serfdom, the tolerance of non-Catholics, & deregulation of the grain markets.

The ruling class disliked all of his reforms, & when the harvest failed & the people were starving, all factions blamed him for every wrong.  His extremely conservative values had him criticized as being a tyrant, and he was accused of tieing himself secretly to political alliances with other countries to save himself.

With the undermining of the monarchy as the established power, a republic was proposed, & real conflict ensued.  In the middle of civil unrest, he & his queen were killed.

(portraits:  Louis XVI in coronation robes & his official portrait; below: Marie Antoinette with 2 of their children in about 1785)