Pierre de Cossé, 12th Duke of Brissac (13 March 1900 – 4 April 1993), was a French aristocrat and author who wrote historical memoirs. He held the French noble title of Duke of Brissac from 1944 to 1993. His father-in-law was Eugène Schneider II, while Maurice Herzog was his son-in-law.

He was born in 1900 in Paris, France.^[1] His father, François de Cossé, was the 11th Duke of Brissac from 1883 to 1944. His mother was Mathilde de Crussol d'Uzès, younger daughter of the 12th Duke of Uzès and his wife, Anne de Rochechouart de Mortemart.^[2]

He wrote historical memoirs, and four of his memoirs were about his family, the Dukes of Brissac.^[3] Moreover, he wrote the preface of Guide du protocole et des usages, a book on good manners written by Jacques Gandouin [fr] in 1979.^[1]

In 1924, he married Marie Zélie Antoinette Eugénie Schneider (1902–1999), known as May Schneider, the daughter of French industrialist Eugène Schneider II.^[4] They resided at the Château de La Celle [fr] in La Celle-les-Bordes, France.

They were the parents of two sons and two daughters:^[1]

1. Marie Pierre de Cossé (b. 1925), who married Simon Nora in 1947. They divorced in 1954 and she married, secondly, Maurice Herzog in 1964.
2. François de Cossé, 13th Duke of Brissac (1929–2021), who married Jacqueline Alice de Contades, daughter of Count André de Contades and Daisy Thome, in 1958.
3. Giles de Cossé (1935–2001).
4. Elvire de Brissac (b. 1939), a novelist.^[5]

He died in 1993 in Paris.^[1]

• Grand Master of the Order of Saint Lazarus

• La duchesse d'Uzès (Paris, Gründ, 1950, 201 pages).
• Les Brissac, Maison de Cossé (Paris: Éditions Fasquelle, 1973, 448 pages).
• A la Billebaude à travers l'Yveline (Chaumont, France: Éditions Crépin-Leblond, 1955, 214 pages).
• Chasse (Chaumont, France: Éditions Crépin-Leblond, 1957, 109 pages).
• Nord Kapp ou la Norvège vue par un Français (Paris: Éditions Del Duca, 1967).
• En d'autres temps (1900-1939) (Paris: Grasset, 1972, 455 pages).
• La suite des temps (1939-1958) (Paris: Grasset, 1974).
• Le temps qui court (1959-1974) (Paris: Grasset, 1977).
• Le château d'en face (1974-1985) (Paris: Grasset, 1986).