Louis Antoine Léon de Saint-Just (; 25 August 1767 – 28 July 1794) was a military and political leader during the French Revolution. The youngest of the deputies elected to the National Convention in 1792, Saint-Just rose quickly in their ranks and became a major leader of the government of the French First Republic. He spearheaded the movement to execute King Louis XVI and later drafted the radical French Constitution of 1793.