Rezé (French: [ʁəze] ⓘ; Breton: Reudied, Gallo: Rezae) is a commune (municipality) and former bishopric in the Loire-Atlantique department in the Pays de la Loire region of western France.

Being populated by the Ambilatres tribe, whose location on the south bank of the lower Loire is not established with certainty, between Armorica and Celtica Gaul.

Rezé was an important port on the south shore of the Loire, established opposite the port of Namnetes, located north of the Loire, Nantes - Contigwic of its Gaulish name - and it is experiencing rapid development, which suggests a strong power of attraction, a place for meetings and trade between the various Celtic tribes of the region (Veneti, Namnetes, Ambilatres, Andecavis and of course Pictones).

In feudal times, it was the capital of Pays de Retz which means “Land of Rezé” within the Duchy of Brittany, after the invasion of the Bretons.

It is limited north by the Loire, east by the Sèvre Nantaise and the Ilette, west by the Jaguère and south by the boulevard périphérique of Nantes.