French political and social leader during the Second Empire who played an important part in the coup d'état of Dec. 12, 1851, which eventually led to the establishment of Charles Louis-Napoléon Bonaparte, Morny's half brother, as Emperor Napoleon III.

Morny was the illegitimate son of Hortense de Beauharnais (the estranged wife of Louis Bonaparte, a brother of Napoleon I) by Charles-Joseph, comte de Flahaut. He affected the fictitious title of comte (count) de Morny (he was not created a duke until late in life). He began his career as a lieutenant in the French Army, serving mainly in Africa (1832–36), but neither his interests nor his ambitions were military. Above all addicted to social pleasures, he resigned his commission and devoted himself to Parisian society and to making a fortune by speculation and by manufacturing beet sugar. He was elected to represent Clermont-Ferrand in the Chamber of Deputies in 1842 and again in 1846 but did not reach the first rank in politics until his half brother, Louis-Napoléon, was elected president of the republic in 1848. He was elected deputy for Puy-de-Dôme in 1849.

Becoming minister of the interior on the day of Louis-Napoléon's coup, Morny organized the plebiscite that made Louis-Napoléon dictator. Soon resigning his ministry, he served briefly as ambassador to Russia (1856) and then became president of the legislature. In this office he abandoned his formerly reactionary role and tried to persuade Napoleon III to give the country more liberty. He saw that Napoleon's dictatorial power could not last and urged him to yield it voluntarily rather than be compelled to do so. In any case, in spite of occasional dissensions, Morny's influence with the emperor remained very great, and he was created a duke in 1862. His health, however, undermined by a ceaseless round of political and financial business, of fashionable life and dissipation, was giving way and was further injured by indulgence in quack medicines. The emperor and the empress visited him just before his death in Paris.

Morny's valuable collection of pictures and art objects was sold after his death. In spite of his undoubted wit and social gifts, Morny failed to secure the distinction that he desired as a dramatist, and none of his plays, which appeared under the pseudonym of M. de St. Rémy—Sur la grande route (“On the Grand Route”), Monsieur Choufleury restera chez lui (“Monsieur Choufleury Will Remain at Home”), and the Finesses du mari (“The Husband's Finesses”), among others—met with any considerable success on the stage.