Messei (French pronunciation: [mɛsɛ] ) is a commune in the Orne department in north-western France.

The commune is made up of the following collection of villages and hamlets, La Pacotière, La Bondière, Les Buissons, Les Pasquières, Les Genétés, La Balonnière, La Haguerie, Messei, La Cheminière, Le Gué, La Bruyère and La Merrie.

It is 1,320 hectares (5.1 sq mi) in size. The highest point in the commune is 215 metres (705 ft).

There are three watercourses that traverse through the commune, the river Varenne, La Vere and a stream called the Blanche-Lande.

The commune has one building listed as a Monument historique, which are the remains of the old 11th-century castle in Messei and listed in 1975.

• Foulques du Merle - (1239 - 1314) was Seigneur of Gacé and Bellou-en-Houlme, and Baron of Le Merlerault, Briouze and Messei.
• Émile Deshayes de Marcère (1828-1918) - last surviving senator for life of the Third Republic was Mayor here, and later died here.

• Communes of the Orne department