|Full name||Julen Arellano Sandúa|
|Date of birth||8 January 1997|
|Place of birth||Ablitas, Spain|
|Height||1.78 m (5 ft 10 in)|
|Playing position||Left back|
* Senior club appearances and goals counted for the domestic league only and correct as of 12 March 2017|
‡ National team caps and goals correct as of 14 August 2015
Born in Ablitas, Navarre, Arellano joined CA Osasuna's youth setup in 2010, aged 13, after starting it out at CD Aluvión. On 15 April 2011 he joined FC Barcelona, being initially assigned to the Cadete squad.
On 15 April 2015 Arellano agreed a contract with Bilbao Athletic, with the deal being effective on 30 June. He made his professional debut on 21 November, coming on as a second-half substitute for Aitor Seguín in a 0–0 home draw against UD Almería for the Segunda División championship.
- "El Bale del Barça" [Barça's Bale] (in Spanish). El Mundo Deportivo. 8 November 2013. Retrieved 11 August 2015.
- "El Barça ficha a Julen Arellano, cadete de Osasuna" [Barça signs Julen Arellano, cadete from Osasuna] (in Spanish). Diario de Navarra. 15 April 2011. Retrieved 11 August 2015.
- "Un juvenil navarro del Barça llegará al Athletic" [A Navarrese juvenil from Barça will arrive at Athletic] (in Spanish). El Correo. 15 April 2015. Retrieved 11 August 2015.
- "Athletic Club signs Julen Arellano". Athletic Bilbao. 30 June 2015. Retrieved 11 August 2015.
- "Bilbao Athletic y Almería siguen encallados en la zona baja" [Bilbao Athletic and Almería remain stranded in the lower zones] (in Spanish). Marca. 21 November 2015. Retrieved 21 November 2015.
- "Julen Arellano vuelve a Osasuna" [Julen Arellano returns to Osasuna] (in Spanish). CA Osasuna. 26 August 2016. Retrieved 19 September 2016.