Antoine Pierre Joseph Marie Barnave (October 22, 1761—November 29, 1793), was a French politician, and, together with Honoré Mirabeau, the most influential orators of the French Revolution.

He was born at Grenoble in Dauphiné, of a Protestant family. His father was an advocate at the Parlement of Grenoble, and his mother was an upper-class educated woman. It was she who educated her son because, being a Protestant, he could not attend school. Barnave was prepared for a career in law, and at the age of twenty-two made himself known by a speech pronounced before the local Parlement on the division of political powers.

Dauphiné was one of the first of the provinces of France to be touched by the revolutionary ideals, and Barnave was one of the first to give voice to the general feeling, in a pamphlet entitled Esprit des édüs enregistrés militairement le 20 mai 1788. He was immediately elected deputy, with his father, to the states of Dauphiné, and took a prominent part in their debates.

A few months later he became better known, when the States-General were convoked at the Palace of Versailles for May 5, 1789, and Barnave was chosen deputy of the Third Estate for his native province.

He soon rose to prominence in the National Assembly, becoming the friend of most of the leaders of the party originating in the Third Estate, and formed with Adrien Duport and Alexandre Lameth the group known during the Constituent Assembly as "the triumvirate". He took part in the conference on the claims of the three orders, drew up the first address to King Louis XVI, and supported the proposal of Emmanuel Joseph Sieyès that the Assembly should declare itself "National". Until 1791, he was one of the main members of the club known later as the Jacobins, of which he drew up the manifesto and first rulebook.

Although a partisan of political freedoms, he hoped to preserve revolutionary liberties together while maintaining the ruling House of Bourbon. Subject to the more radical forces, Barnave took part in the attacks on the monarchy, on the clergy, on Roman Catholic Church property, and on the provincial Parlements. On several occasions he stood in opposition to Mirabeau. After the storming of the Bastille, he wished to save the throne. He advocated the suspensory veto, and the establishment of trial by jury in civil causes, but voted with the Left against the system of two chambers.

His conflict with Mirabeau on the question of assigning to the King the right to make peace or war (from May 16 to 23, 1791) was one of the main episodes of the Assembly's mandate. In August 1790, after a vehement debate, he fought a duel with Jacques Antoine Marie de Cazalès, in which the latter was slightly wounded. About the close of October 1790, Barnave was called to the presidency of the Assembly. On the death of Mirabeau a few months later, Barnave paid a high tribute to his worth and public services, designating him the "William Shakespeare of oratory".

On the arrest of the king and the royal family during the Flight to Varennes, Barnave was one of the three appointed to conduct them back to Paris. During the journey, he began to feel compassion for Queen Marie-Antoinette, and subsequently attempted to do what he could to alleviate their sufferings. In one of his most powerful speeches, he maintained the inviolability of the king’s person.

Barnave led the Feuillants out of the Jacobin Club in early 1791, and their faction entered a conflict with the Girondists after they opposed war with Habsburgs, and were driven out of the Assembly. His public career came to an end, and he returned to Grenoble at the beginning of 1792. His sympathy and relations with the royal family, to whom he had submitted a plan for a counter-revolution, and his desire to check the violence of the Revolution, brought on him suspicion of treason.

He was denounced (August 15, 1792) in the Legislative Assembly, arrested and imprisoned for ten months at Grenoble, then transferred to Fort Barraux, and in November 1793 to Paris (during the Reign of Terror). On November 28 he appeared before the Revolutionary Tribunal. He was condemned on the evidence of papers found in the Tuileries Palace, and guillotined the next day, alongside Marguerite-Louis-François Duport-Dutertre.