Sergio Castel Martínez (born 22 February 1995), is a Spanish Footballer who plays as a forward for Indian club Jamshedpur FC, on loan from Atlético Madrid B.
Born in Artea, Biscay, Basque Country,Spain Castel made his senior debut with Tercera División side UE Rubí, in the 2012–13 season. In July 2013, he joined CA Osasuna and returned to the youth setup, but on 31 January of the following year, he was loaned to CD Tudelano in Segunda División B, for six months.
In July 2014, Castel moved to CD Lealtad also in the third division, but left the club in November after featuring rarely. He then signed for Las Rozas CF, a club he already represented as a youth, before moving abroad to Bendigo City FC in Australia.
Castel only returned to Spain on 25 January 2017, after agreeing to a contract with AD Alcorcón's reserves in the fourth division. On 18 August, he moved to third level club UD San Sebastián de los Reyes.
In August 2019, after scoring a career-best 13 goals for Sanse, Castel joined Atlético Madrid, being initially assigned to the B-team; subsequently, he was loaned to Indian Super League side Jamshedpur FC until the end of the year.