Samuel "Samu" Castillejo Azuaga (born 18 January 1995) is a Spanish professional footballer who plays as a winger for Malaysia Super League club Johor Darul Ta'zim.

Castillejo was born in Barcelona, Catalonia where his father, a Guardia Civil officer, was stationed at the time; the family resettled in Málaga, Andalusia within a few months.

[2] He graduated from Málaga CF's youth system, made his senior debut with the reserves in 2011 aged only 16, and went on to play three full seasons in Tercera División.

[5] Castillejo made his debut with the first team on 29 August 2014, coming on as a substitute for fellow youth graduate Juanmi in the 57th minute of a 3–0 La Liga away loss to Valencia CF.

[7] Castillejo joined Villarreal CF on 18 June 2015 alongside his Málaga teammate Samu García, signing a five-year deal.