Athletic Club "B", commonly known as Bilbao Athletic, is the reserve team of Athletic Club, a football club based in Bilbao, in the autonomous community of Basque Country in Spain. The team are playing in the Segunda Federación – Group 2. Founded in 1964, the team holds home matches at the small stadium attached to the club's training facility at Lezama, holding 3,250 spectators or occasionally at San Mamés Stadium, with its 53,500-seat capacity, for important fixtures.

The Lezama Facilities, are the training ground and academy of the Primera Division club Athletic Bilbao. Located in the village of Lezama, around 10–15 kilometers east of Bilbao, the facilities were opened in 1971 and currently cover 13 hectares. Athletic's academy is often referred to metonymically as Lezama.