Athletic Club Bilbao is a football club located in the city of Bilbao, Biscay Province, Basque Autonomous Community, northern Spain. Founded in 1898, it is the second oldest football club in Spain.  
The club is a founding member of the Spanish La Liga and has never been relegated since 1928. Only Real Madrid and Barcelona hold this honor simultaneously. The club only uses Basque players and had no commercial advertisements on their jerseys before 2008. The team's nickname is' Basque Lion '.
In a semi-final second leg match of the Copa del Rey that ended in the early hours of March 5, 2021 Beijing time, Athletic Bilbao defeated Levante 2-1 away, eliminating their opponents with a total score of 3-2. They advanced to the Copa del Rey final with 39 appearances, equaling Real Madrid, second only to Barcelona with 42 appearances. Due to the King's Cup final of the 2019-20 season being held on April 4, 2021 (Beijing time), Athletic Bilbao became the first team in history to participate in two King's Cup finals in the same month.  
On December 5, 2024, in the 19th round of La Liga, Athletic Bilbao defeated Real Madrid 2-1 at home, ending the record of 18 consecutive winless matches against Real Madrid in La Liga and becoming the only team in all competitions of 2024 to have defeated Real Madrid and Barcelona.