The British Rail Class 319 is a dual-voltage electric multiple unit train capable of operating on 25 kV 50 Hz AC from overhead wires or 750 V DC from a third rail. They were built by British Rail Engineering Limiteds York carriage works for use on north-south cross-London services.

Built in two batches in 1987 88 and 1990 for BRs Network SouthEast sector the units were primarily used on the then-new Thameslink service operating from Bedford to Brighton and various other destinations south of London. The majority of the fleet remained in use on the Thameslink network after its reshaping and privatisation in 1997 with a few units moving to Southern. Some of the fleet was also used on various other services operating out of London Victoria including flagship expresses to Brighton.

Since delivery of new Class 700 rolling stock for Thameslink services commenced in 2015 Class 319 units have been redeployed for use in the North West of England on newly electrified lines as well as being converted to self-powered trains for use away from the electricity supply.