Louis Antoine Sophie de Vignerot du Plessis, 4th Duke of Richelieu (4 February 1736 – 1791), was a French nobleman and general.
He was the son of Louis François Armand de Vignerot du Plessis (1696–1788), 3rd Duke of Richelieu, Marshal of France and an expert courtier, and of Marie Élisabeth Sophie de Lorraine (daughter of Anne Marie Joseph de Lorraine.
Madame de Pompadour wished Antoine to marry her daughter, but his father avoided that demand by pretending that Antoine's mother was a Princess of Lorraine (much superior to the house of Richelieu) and that he would thus need the permission of the head of that house (Emperor Francis I) for the marriage.
A first cousin was Marie Charlotte, Princess of Beauvau, wife of Charles Juste de Beauvau and daughter of the Duke of Bouillon.
He succeeded his father as a premier gentilhomme de la chambre to King Louis XVI, and later became a maréchal de camp and lieutenant général (1780).