Athletic Bilbao

Athletic Club, most often known in English as Athletic Bilbao, is a football club which plays in Spain.
The club formed from a merger of two football clubs ; Bilbao F.C. and Athletic Club in 1903.
Athletic Bilbao is known for only utilizing players from the historic basque territory, which includes the Basque Country in Spain and France such as the region of Navarre.
Rivalries.
Athletic Club has three major rivalries: Real Sociedad de San Sebastian, FC Barcelona and Real Madrid.
The Rivalry with Real Sociedad is due to the location, because both teams are from the Basque Country. The rivalry also took place because of the rule to only sign players from the basque territory, yet Real Sociedad abondoned the rule in the 1980s.
The rivalries with Real Madrid established itself because of the political circumstances. Both the Basque Country and Catalunya were had massive issues with the central goverment under Dictator Franco in Madrid, who forbid their language and traditions for a greater spanish empire. Franco heavily supported the capitals team, Real Madrid, which caused tensions with supporters of Athletic Club.
The rivalry with FC Barcelona also is a result of the Franco-era. FC Barcelona, located in Catalunya, had the same issues with the central government such as the Basque Country. As a result of this circumstance, a rivalry between the Basque Country and Catalunya happened, which translated in football. As both Athletic Club and the FC Barcelona are the most important teams of their regions, they were the protagonists for this rivalry. 
Even with Spain being democratic since Franco's in 1975, both rivalries with Real Madrid and FC Barcelona are still on-going. 
Honours.
International tournaments.
"Runners-up:" 2011-2012