Euskotren Trena, formerly known just as Euskotren is a commuter, inter-city and urban transit train-operating company that operates local and inter-city passenger services in the provinces of Biscay and Gipuzkoa, in the Basque Country, Spain. It is one of the four commercial brands under which Euskotren operates, as a public company managed by the Basque government. The entire 181.1-kilometre (112.5 mi) network uses 1,000 mm narrow gauge rail tracks which have been owned by the Basque Government since their transferral from the Spanish government; the rail tracks and stations were part of the FEVE network until its transferral. Euskotren Trena also operates the Donostia/San Sebastián metro under the brand Metro Donostialdea.

Biscay is a province of Spain and a historical territory of the Basque Country, heir of the ancient Lordship of Biscay, lying on the south shore of the eponymous bay. The capital and largest city is Bilbao.