Pierre Ambroise François Choderlos de Laclos (18 October 1741 – 5 September 1803) was a French novelist, official and army general, best known for writing the epistolary novel Les Liaisons dangereuses (Dangerous Liaisons).

A unique case in French literature, he was for a long time considered to be as scandalous a writer as the Marquis de Sade or Nicolas-Edme Rétif. He was a military officer with no illusions about human relations, and an amateur writer; however, his initial plan was to "write a work which departed from the ordinary, which made a noise, and which would remain on earth after his death"; from this point of view he mostly attained his goals, with the fame of his masterwork Les Liaisons dangereuses . It is one of the masterpieces of novelistic literature of the 18th century, which explores the amorous intrigues of the aristocracy. It has inspired a large number of critical and analytic commentaries, plays, and films.

Laclos was born in Amiens into a bourgeois family, and in 1760 was sent to the École royale d'artillerie de La Fère, ancestor of the École polytechnique. As a young lieutenant, he briefly served in a garrison at La Rochelle until the end of the Seven Years War (1763). Later he was assigned to Strasbourg (1765–1769), Grenoble (1769–1775) and Besançon (1775–1776).

Despite being promoted to captain (1771), Laclos grew increasingly bored with his artillery garrison duties and the company of the soldiers, and began to devote his free time to writing. His first works, several light poems, were published on the Almanach des Muses. Later he wrote an Opéra-comique, Ernestine, inspired by a novel by Marie-Jeanne Riccoboni. Its premiere on 19 July 1777, in presence of Queen Marie-Antoinette, was a failure. In the same year he created a new artillery school in Valence, which was to include Napoleon among its students. At his return at Besançon in 1778, Laclos was promoted second captain of the Engineers. In this period he wrote several works, which showed his great admiration of Jean-Jacques Rousseau.

In 1779 he was sent to Île-d'Aix to assist Marc-René de Montalembert in the construction of fortifications there against the British. He however spent most of his time writing his new epistolary novel, Les Liaisons Dangereuses, as well as a Letter to Madame de Montalembert. When he asked for and was granted six months of vacation, he spent the time in Paris writing.

Les Liaisons Dangereuses was published by Durand Neveu in four volumes on 23 March 1782, turning into a widespread success (1,000 copies sold in a month, an exceptional result for the times). Laclos was immediately ordered to return to his garrison in Brittany; in 1783 he was sent to La Rochelle to collaborate in the construction of the new arsenal. Here he met Marie-Soulange Duperré, 18 years his junior, whom he would marry in 1786. The following year he began a project of numbering Paris' streets.

In 1788 Laclos left the army, entering the service of Louis Philippe, Duke of Orléans, for whom, after the outbreak of the French Revolution, he carried forward with intense diplomatic activity. Captured by the Republic ideals, he left the Duke to obtain a place as commissar in the Ministry of War. His reorganization has been credited as having a role in the Revolutionary Army victory in the Battle of Valmy. Later, after the desertion of general Charles François Dumouriez, he was however arrested as "Orleaniste", being freed after the Thermidorian Reaction.

He thenceforth spent some time in ballistic studies, which led him to the invention of the modern artillery shell. In 1795 he requested of the Committee of Public Safety reintegration in the army, which was ignored. His attempts to obtain a diplomatic position and to found a bank were also unsuccessful. Eventually, Laclos met the young general and recent First Consul, Napoleon Bonaparte, and joined his party. On 16 January 1800 he was reinstated in the Army as Brigadier General in the Armée du Rhin, taking part in the Battle of Biberach.

Made commander-in-chief of Reserve Artillery in Italy (1803), Laclos died shortly afterward in the former convent of St. Francis of Assisi at Taranto, probably of dysentery and malaria. He was buried in the fort still bearing his name (Forte de Laclos) in the Isola di San Paolo near the city, built under his direction. Following the restoration of the House of Bourbon in southern Italy, his burial tomb was destroyed; it is believed that his bones were tossed into the sea.