The Organization for the Protection of the People's Struggle (Greek: Οργάνωση Περιφρούρησης Λαϊκού Αγώνα, abbreviated ΟΠΛΑ – OPLA, an acronym meaning "weapons" in Greek) was a special division of the Communist Party of Greece (KKE) during the Axis Occupation of Greece in World War II.
It acted especially in Thessaloniki and Northern Greece in 1946–1947 (in these regions the name of the organization was Close Self-Defense, Στενή Αυτοάμυνα in Greek).
One of its more notable later actions was the assassination of Justice Minister Christos Ladas (who had signed the execution of hundreds of communists) in Athens on 1 May 1948, by OPLA and KKE member Efstratios (Stratos) Moutsogiannis.
During the Greek Civil War, OPLA turned the monastery of St. George in Feneos into a concentration camp and killing ground for those they deemed "reactionaries".
The concentration camp was well-organized for mass killings, with 6-7 resident killers that worked round the clock in busy times.