Maximilien de Robespierre
He executed King Louis XVI because he was convicted of treason.  Under the advice of Robespierre, the Committee of Public Safety came to control France. The period that the Committee of Public Safety ruled France is known as “The Reign of Terror” and Maximilien de Robespierre was their leader. In the Thermidorian Reaction Robespierre was caught and executed with 21 of his followers with a guillotine.  The National Convention were the people who overthrew Maximilien de Robespierre.