Terrassa (Catalan pronunciation: [təˈrasə]) is a Spanish city in the east central region of Catalonia, in the province of Barcelona, comarca of Vallès Occidental, of which it is the cocapital along with Sabadell.

The city is located in the Catalan Prelitoral depression (Depressió Prelitoral), at the feet of the Prelitoral mountain range (Natural reserve of Sant Llorenç del Munt) and the average altitude of the city is 277 meters above sea level. It is 20 and 18 kilometres from Barcelona and Montserrat respectively.