Trollhättan (Swedish pronunciation: [trɔlhɛtan]) is a city and the seat of Trollhättan Municipality, Västra Götaland County, Sweden with 46,457 inhabitants in 2010. It is located 75 km north of Sweden's second-largest city, Gothenburg.

Trollhättan was founded by the river Göta älv, at the location of Trollhättan Falls. The site was first mentioned in literature from 1413. For centuries, Trollhättan was an obstacle for the boats travelling the river, up until a lock system was completed in the 19th century. It has since been updated several times and the present locks were finished in 1916.

In the late 19th century, hydropower was developed in Trollhättan. The Swedish energy corporation Vattenfall ("waterfall") took its name from the falls in Trollhättan. Today the city has two operational hydropower stations, Olidan and Håjum. The hydropower has helped the city in its industrial revolution.

Trollhättan was granted city rights (which today have no legal effect, but is purely historical) in 1916 at which time it had about 15,000 inhabitants, now grown to 54,000.