Former Greek prime minister Costas Simitis died Sunday at the age of 88, state-run Ertnews reported. Simitis had not been facing a particular health problem. A former prime minister and one of the founding members of the socialist party Panhellenic Socialist Movement (PASOK), Simitis left his mark on the political life of the country. He succeeded PASOK founder Andreas Papandreou as party leader and served as prime minister of Greece from 1996 to 2004. He played a critical role in the country’s adoption of the euro in 2001.