|Full name||Julen Castañeda Nuin|
|Date of birth||14 November 1990|
|Place of birth||San Sebastián, Spain|
|Height||1.80 m (5 ft 11 in)|
|Playing position||Centre back|
|2010–2013||Real Sociedad B||88||(4)|
|* Senior club appearances and goals counted for the domestic league only and correct as of 21 May 2017.
Castañeda scored his first goal in the competition on 9 November 2014, netting his side's second in a 3–3 home draw against Recreativo de Huelva. He was released in 2015, and subsequently resumed his career in the third division by representing Burgos CF and Racing de Santander.
- Castañeda firmará dos temporadas con la Ponferradina (Castañeda will sign for two seasons with Ponferradina); Marca, 14 July 2013 (in Spanish)
- Strahman acaba con la maldición cordobesista de la primera jornada (Strahman ends Córdoba's first matchday curse); Marca, 17 August 2013 (in Spanish)
- El Decano iguala en el minuto 93 un duelo con muchas alternativas (The Dean ties a duel with many alternatives in the 93rd minute); Marca, 9 November 2014 (in Spanish)
- Julen Castañeda, nuevo lateral izquierdo para el Burgos CF (Julen Castañeda, new left back for Burgos CF); Diario de Burgos, 29 January 2016 (in Spanish)
- Héber Pena y Julen Castañeda, primeros refuerzos racinguistas (Héber Pena and Julen Castañeda, first racinguista additions); Racing Santander, 11 July 2016 (in Spanish)