Agios Alexandros is a settlement in the northeastern part of the Aegean island of Lemnos, Greece. It is part of the municipal unit of Moudros and the community of Kontopouli. The population was 4 at the 2021 census. It is located north of the Alyki Lagoon, 4 km southwest of Panagia and 5 km northeast of Kontopouli.