Castres (; Castras in the Languedocian dialect of Occitan) is a commune, and arrondissement capital in the Tarn department and Midi-Pyrénées region in southern France. It lies in the former French province of Languedoc.
Castres is (after Toulouse, Tarbes and Albi) the fourth largest industrial centre of the predominantly rural Midi-Pyrénées région and the largest in that part of Languedoc lying between Toulouse and Montpellier.
Castres is noted for being the birthplace of the famous socialist leader Jean Jaurès and home to the important Goya Museum of Spanish painting.
Castres may refer to:
- Castres, a commune in the Tarn department in the Midi-Pyrénées region
- Castres, Aisne, a commune in the Aisne department in the Picardy region
- Castres-Gironde, a commune in the Gironde department in the Aquitaine region
- Arrondissement of Castres, an arrondissement in the Tarn department in the Midi-Pyrénées region