Konstantinos Papastavrou (Greek: Κωνσταντίνος Παπασταύρου), known with the nickname Mavromatis (Μαυρομάτης, "Black-eye") was a Greek chieftain of the Macedonian Struggle.
| Honorific Prefix: | Kapetan (Chieftain) |
| Konstantinos Papastavrou | |
| Native Name: | Κωνσταντίνος Παπασταύρου |
| Birth Date: | c. 1880s |
| Birth Place: | Mavrovo, Monastir Vilayet, Ottoman Empire (now Mavrochori, Greece) |
| Nickname: | Kapetan Mavromatis (Καπετάν Μαυρομάτης) |
| Allegiance: | Kingdom of Greece |
| Branch: | HMC |
| Battles: | Macedonian Struggle |
Papastavrou was born in the 1880s in Mavrovo (now Mavrochori) in Kastoria. Because of his characteristic eyes, he received the nickname "Mavromatis" meaning "Black-eyed".
He set up his own armed group, consisting of local Greeks of Mavrovo and other villages nearby and acted in the regions of Kastoria, Eordaia and Amyntaio during throughout the Macedonian Struggle against Bulgarian komitadjis and specific Ottoman targets. His body consisted of around 45 men.
He collaborated with chieftains Alexandros Georgiadis and Stergios Kountouras on several occasions.