Konstantinos "Kostas" Vasileiadis (alternate spellings include: Costas, Vasiliadis, Vassiliadis) (Greek: Κωνσταντίνος "Κώστας" Βασιλειάδης; born March 15, 1984) is a Greek professional former basketball player who last played for Cáceres Ciudad del Baloncesto of LEB Oro.

Vasileiadis was a famous and popular player while he played with the Spanish giants Málaga during the 2006–07 season.

The Spanish side was able to make an impact in European competitions, partly due to the play and efforts of Vasileiadis, while he was a member of the club.

On July 12, 2007, he signed a contract with the Greek EuroLeague giants Olympiacos, despite them being rivals to his personal favorite club and previous team, PAOK.

[9] On December 5, 2017, he left Trikala and signed with Iberostar Tenerife for the rest of the 2017–18 ACB season.

[11] On July 16, 2020, Vasileiadis and Obradoiro parted ways and his third stint with the Spanish club officially ended.

The silver medal was also won and he was voted to the All-Tournament Team, at the 2005 FIBA Under-21 World Cup, which was held in Argentina.