Augustin Bon Joseph de Robespierre (21 January 1763 – 28 July 1794) was the younger brother of French Revolutionary leader Maximilien Robespierre.
He was born in Arras, the youngest of four children of the lawyer Maximilien-Barthelemy-François de Robespierre and Jacqueline-Marguerite Carraut, the daughter of a brewer. His mother died when he was one year old, and his grief-stricken father abandoned the family to go to Bavaria, where he died in 1777. He was brought up by an aunt and trained as a lawyer. His brother Maximilien had won a scholarship from the Abbey of St. Vaast to pay for his studies at the Lycée Louis-le-Grand and had been such an outstanding student that when he obtained his degree in law, he asked the Abbot, Cardinal de Rohan, if he would transfer the scholarship to Augustin to allow him to follow the same career. The Cardinal agreed and Augustin took up his brother's place studying law.
Although his political views were very similar to those of his brother, Augustin was very different in character. Handsome, he was also fond of good food, gaming and the company of women. At the outset of the Revolution, Augustin was prosecutor-syndic of Arras. He founded a political club in the town and wrote to his brother to secure its affiliation with the Jacobins in Paris. In 1791, he was appointed Administrator of the département of Pas-de-Calais.
Augustin unsuccessfully stood for election to the new Legislative Assembly in Arras in August 1791, but his views were too radical for the town, which elected another young lawyer, Sixte François Deusy instead. However on 16 September 1792, Augustin was elected to the National Convention,19th out of 24 deputies, with 392 votes out of 700 cast, by the voters of Paris, and he joined his brother in The Mountain and the Jacobin Club. At the Convention he distinguished himself by the vehemence of his attacks on the royal family and on aristocrats. During the trial of Louis XVI he voted for the death penalty to be applied within 24 hours.