CD Baskonia

Founded in 1913 and named after a local iron and steel-working works (later owned by the Altos Hornos de Vizcaya company), Basconia reached the national third level (Tercera División) thirty years later. The club played in the second tier for six seasons (1957–1963), but this was before the creation of the regionalised new third division in the 1970s. In 1997, Basconia became Basque neighbours Athletic Bilbao's feeder club, not being eligible for promotion if the reserves, Bilbao Athletic, playing at the level above, do not attain the same goal. The primary function of the agreement is to aid the development of young players in a challenging environment while keeping them in the same group setting and tactical system under the close guidance of the parent club; a number of teenagers who spent one or two seasons at Basconia have become professionals at Athletic Bilbao, eventually playing in La Liga and UEFA competitions. In January 2020 it was confirmed that the partnership, due to expire that summer, had been renewed for another three years to 2023. Basconia's place in Athletic's club structure means that the squad changes greatly each season. About half of the players move up to play for Bilbao Athletic, or go out on loan to other local clubs playing at Segunda Federación level. They are replaced by graduates, usually 17 or 18 years old, from the previous year's Juvenil A team. Typically the squad is expanded further with new signings from the region's youth clubs, the most…

Tercera División Winners: 1956–57 Winners (3): 1984–85, 1997–98, 2002–03