Athanasios 'Thanasis' Kostanasios (; born 11 January 1999) is a Greek professional footballer who plays as an attacking midfielder for Gamma Ethniki club Panachaiki.
Club career Born in Piraeus, Kostanasios came through the academy of Olympiacos, featuring for the club's Under-19 and Under-20 team and making one first team appearance in a Super League 1 match in May 2018. From Olympiacos, Kostanasios would join Super League 2 side Ergotelis, where he made 51 appearances with seven goals across two seasons.
In July 2022, Kostanasios joined Athens Kallithea FC.
In July 2026, Kostanasios joined Panachaiki.
International career At international level, Kostanasios earned 26 caps with five goals representing Greece from the Under-16 to Under-20 levels.
Honours Olympiacos Super League: 2019–20
References