The Re 456 is a type of standard-gauge electric locomotives that is being used by three private operators in Switzerland. It was originally developed for the Bodensee Toggenburg Railway (BT) which needed a locomotive that could haul passenger trains at 130 km/h, but also freight trains up to 1,500 tonnes. They have an axle load of only 17 tonnes and a continuous output of 3,200 kW. Three-phase traction motors are being fed by GTO thyristors.

The BT received six locomotives in 1987. In the following year and in 1993, the Sihltal Railway also received six locomotives of this type. The Vereinigte Huttwil-Bahnen became the third customer with two locomotives. They are also called Re 4/4 by their operators. A direct development is the Re 450 for S-Bahn service that has only one cab.