Renfe (from the Spanish acronym Red Nacional de los Ferrocarriles Españoles - Spanish National Railway Network), also known as Renfe Group, and officially Renfe-Operadora, is the state-owned company which operates freight and passenger trains on the 1,668 mm (5 ft 5+21⁄32 in) Iberian gauge, the 1,435 mm (4 ft 8+1⁄2 in) standard gauge and the 1,000 mm (3 ft 3+3⁄8 in) metre gauge Spanish railway networks.

The company operates some 12,000 km (7,500 mi) of railways, 7,000 km (4,300 mi) of them electrified. Most of the tracks are constructed to the broad "Iberian gauge" of 1,668 mm (5 ft 5+21⁄32 in), the same as that used in Portugal but wider than the international gauge of 1,435 mm (4 ft 8+1⁄2 in) which is standard in neighbouring France, most of western and central Europe, and most of the rest of the world. The newer high-speed (AVE) network has been built to the international standard gauge of 1,435 mm for the connection to the rest of the European railway system. For this reason, the 1,435 mm gauge is generally termed "European gauge" in Spain.

The Spanish high-speed system is called AVE (Alta Velocidad Española, meaning "Spanish High Speed"). The logo incorporates a feature which resembles a bird (ave in Spanish). The high-speed lines are built to the standard European gauge (1,435 mm or 4 ft 8+1⁄2 in).

Construction of the high-speed rail line between Madrid and Seville began in 1988 and operation commenced in 1991. Train speed on the Seville line is 300 km/h (190 mph). The second high-speed rail line (Madrid to Barcelona) was completed in 2007 with the inaugural service commencing at 06:00 on 20 February 2008. The operational speed on this route is 350 km/h (220 mph). The greater part of the line (Madrid to Lleida) was placed into service on 11 October 2003, with connection to Huesca from Zaragoza. The third high-speed line (Madrid to Toledo) was opened in November 2005, followed by the spur from Córdoba to Málaga as far as Antequera in 2007. Another high-speed route from Madrid to Valladolid was opened in 2007, the line from Madrid to Valencia was opened in 2010 and the first stage of the high-speed line in Galicia opened in 2011. A line to Lisbon is being designed.

Other lines operated by Renfe include Euromed, a moderate-speed line between Barcelona and Alicante.

In addition to intercity transport, Renfe operates commuter train systems, known as Cercanías (or Rodalies in Catalonia and Cercanías-Aldirikoak in the Basque Country), in eleven metropolitan areas, including Madrid and Barcelona. In some cities, Renfe shares the market with other commuter railway operators, such as FGC in Barcelona.