After that he became a national star in Cyprus and Greece, being part of the Golden Age of the Cypriot and Greek Cinema (1950s–1970s).

Moustakas' international film debut came in 1964 in the Oscar-winning Zorba the Greek starring Anthony Quinn, in which he played Mimithos, the village idiot.

Although not widely advertised, Moustakas in his youth was involved in the Greek Cypriot national liberation struggle of EOKA against British colonialism, acting as a messenger, and writing political graffiti.

[1] Moustakas felt unwell during rehearsals for an upcoming Aristophanes play, and was transferred to the General State Hospital of Athens.

His wife, Maria, died on August 30, 2007, due to Alzheimer, at the age of 66, about 3 months after the death of Sotiris.