Isère (US: ee-ZAIR; French: [izɛʁ] ; Arpitan: Isera; Occitan: Isèra, Occitan pronunciation: [iˈsɛɾa]) is a landlocked department in the southeastern French region of Auvergne-Rhône-Alpes. Named after the river Isère, it had a population of 1,271,166 in 2019. Its prefecture is Grenoble. It borders Rhône to the northwest, Ain to the north, Savoie to the east, Hautes-Alpes to the south, Drôme and Ardèche to the southwest and Loire to the west.

Isère is one of the original 83 departments created during the French Revolution on 4 March 1790. It was established from the main part of the former province of Dauphiné.