Kazakos was born on 29 May 1935 in Pyrgos, Elis, originally from the village of Karyes, Trifylia.

At the age of 18, he settled in Athens to study pedagogy, but his father's left-wing heritage caused him to be rejected by the university.

From 1968 to 1992 he was married to actress Tzeni Karezi, with whom he had a son, also actor Konstantinos Kazakos (b.

Artemis-Georgia died on June 25, 1999, aged 8 months and one week after her baptism, suffering from a rare disease.

Also, he was a founding member of the Hellenic Arab Association and a member of the Actor's Licensing Committee, co-founder of the Free Theatre (together with Leonidas Trivizas) and founder of the Tzeni Karezi Foundation.