Antoine Louis Leon De Saint-Just, a French revolutionist, born at Decize, near Nevers, in 1767 or 1768, guillotined in Paris, July 28, 1794. He early imbibed a very extravagant admiration of the ancient republics, and published several poems, and in 1791 a work entitled Esprit de la révolution et de la constitution de France. Through the influence of Robespierre he was in 1792 elected to the convention. He took the foremost rank among the violent spirits in that body, voted for the immediate execution of Louis XVI., advocated the concentration of all power in the convention, including the supervision of military operations, and urged the reign of terror as the only means of safety for France, declaring that "those who make half-way revolutions only dig their own graves." After the fall of the Girondists he became a member of the committee of public safety, and as commissioner to the army of the Rhine he established the guillotine in Alsace. In February, 1794, he was named president of the convention, and in March made the report against Danton and his partisans which insured their death. With Robespierre and Couthon he formed the triumvirate of the reign of terror. On the 9th Thermidor he tried by speaking to resist the public wrath, but the next day he was executed.

His Oeuvres politiques have been collected (1833-'4), and his life has been written by Fleury (2 vols., 1852) and Hamel (1859).