Leros, also called Lero, is a Greek island and municipality in the Dodecanese in the southern Aegean Sea. It lies 317 kilometres from Athens's port of Piraeus, from which it can be reached by a nine-hour ferry ride or by a 45-minute flight from Athens. It is about 32 kilometres (20 mi) from Turkey. Leros is part of the Kalymnos regional unit. It has a population of 7,992 (2021).

The Dodecanese are a group of 15 larger and 150 smaller Greek islands in the southeastern Aegean Sea and Eastern Mediterranean, off the coast of Turkey's Anatolia, of which 26 are inhabited. This island group generally defines the eastern limit of the Sea of Crete. They belong to the wider Southern Sporades island group.