Theodoros "Thodoris" Vlachos (Greek: Θοδωρής Βλάχος; born 9 July 1969, in Volos) is a retired Greek water polo player and the current coach of the Greece men's national water polo team.

He was also a member of the Greece men's national water polo team.

Under his guidance, Olympiacos won the 2017–18 LEN Champions League in Genoa, after a 9–7 win against home team Pro Recco in the final and completed a Triple Crown, winning the season's all available titles.

[6] In 2014, he became head coach of Greece men's national water polo team,[7] whom he led to the bronze medal at the 2015 World Aquatics Championships in Kazan and the bronze medal at the 2016 World League in Huizhou.

[8] Vlachos, as the head coach of Greece's national water polo team, has attained the silver medal in the Olympic Games of Tokyo in 2020, and also the silver medal in the World Championships at Fukuoka in 2023.