Athanasios Mastrovasilis is a Greek chess grandmaster, born on 20 April 1979. He achieved his Grandmaster title in 2003, becoming the second grandmaster in his family after his brother, Dimitrios Mastrovasilis.
Some notable achievements in his chess career include winning the Greek Junior Championships twice, winning the Greek Individual Championship twice, and guiding Athens Chess Club Agios Thomas to eight Greek Team Championships. He also competed in Olympiads in Turin and Dresden and the European Team Championships.
Mastrovasilis has competed against and drawn with some notable chess players including Magnus Carlsen, Francisco Vallejo Pons, and Andrei Volokitin.
In addition to playing, Mastrovasilis is also a chess coach. He began coaching youth national teams in 2003, and in 2013, he became the head of Greek National Team. Under his leadership, the Greek women's team saw their best result yet in both the Olympiad and European Team Championship in 2013.
Mastrovasilis continues to combine his roles as player and coach. He also composes chess studies and problems and conducts chess seminars and workshops in schools and universities. He earned a degree in Political and Strategic Studies from the Greek Army Academy.
In 2019, he was honoured by the President of Greece with the Commander of the Order of Honor for his contributions to chess in Greece. He is currently considered one of the top chess players in Greece.