Ilias Kostis

Ilias Kostis (; born 27 February 2003) is a Greek footballer who plays as a centre-back for club Castellón.

Club career In 2019, Kostis joined the youth academy of Spanish La Liga side Atlético Madrid from APOEL. Promoted to the reserves in 2022, he quickly established himself as a starter before renewing his contract until 2027 on 9 February 2023.

After helping in the B-team's promotion to Primera Federación, Kostis made his first team debut with Atleti on 4 October 2023, coming on as a late substitute for goalscorer Álvaro Morata in a 3–2 UEFA Champions League win over Feyenoord. In December, however, he suffered a serious muscular injury which sidelined him for nearly six months.

Back to action in May 2024, Kostis regained his starting spot at the B's before suffering a knee injury in October 2025, being sidelined for the remainder of the season. On 31 July 2026, he signed a four-year deal with Segunda División side Castellón.

International career Born in Greece, Kostis represented Cyprus up to the under-21 level, before switching allegiance back to Greece to play for their own under-21 squad in 2023.