Kostis Theos was born in Athens in 1966. He took his first cello lessons at the age of eleven with Dimitris Gouzios and continued with Eleftherios Papastavrou. He studied at the Royal Academy of Music (London) with David Strange, at the Ferenz Liszt Academy (Budapest) with Laszlo Mezö, (funded by the AS Onassis Benefit Foundation) and at East Anglia University with Matthias Feile (MMus). He was a member of the European Union Youth Orchestra and is currently principal cellist of the Athens Symphony Orchestra. He is also a member of the Hellenic Ensemble of Modern Music with which he appears as soloist at concerts with music by contemporary Greek composers. He has appeared extensively at music festivals of chamber and contemporary music and as a composer wrote original music for the documentary series Hellenism and the West, produced by the State Greek TV Channel (ET1), and for the fiction film Eleatis Xenos by Dimos Theos.