ACU may refer to:
The Piranhas River (Portuguese: Rio Piranhas-Açu), also known as the Açu River, is a river of northeastern Brazil. It originates in southeastern Paraíba state, near the border with Ceará, and flows north-northeast through Paraíba and Rio Grande do Norte states to empty into the Atlantic Ocean near Macau. Its chief tributary is the Seridó, which originates in the Borborema Plateau of central Paraíba and flows northwest to meet the Piranhas.
The ACU is an political-cultural venue in the city center of Utrecht, the Netherlands. The name ACU is derived from "Auto Centrale Utrecht" (Car Center Utrecht) and is one of the many signs of its origin as an old squat. Nowadays it is still run by volunteers to keep it an independent and non-profit harbor within Utrecht's nightlife. The ACU hosts a wide range of activities including: concerts, dance nights, political info nights, poetry events, benefits, parties, a venue for meetings and much more. It accommodates an vegan eatery called Kitchen Punx every Tuesday to Saturday.
The car center ACU used to be existed from 1935 to 1967. In the year 1976 the premises was squatted an adapted for habitation. In the course of the years multiple small businesses settled there as well like for example a bike-shop. The residents started an cinema in the former showroom in 1979. After two years the cinema was replaced by an coffeehouse to be able to provide an public space for the squatting community. Eventually this developed in to a venue providing a stage for local and international bands since 1985.