The British Rail Class 373, known in France as the TGV TMST and branded by Eurostar as the Eurostar e300, is a French designed and Anglo-French built electric multiple unit train that was used for Eurostar international high-speed rail services from the United Kingdom to France and Belgium through the Channel Tunnel. Part of the TGV family, it was built with a smaller cross-section to fit the smaller loading gauge in Britain, was originally capable of operating on the UK third rail network, and has extensive fireproofing in case of fire in the tunnel. It is both the second longest—387 metres —and second fastest train in regular UK passenger service, operating at speeds of up to 300 kilometres per hour (186 mph).

Eurostar is an international high-speed rail service in Western Europe, connecting Belgium, France, Germany, the Netherlands and the United Kingdom.