Gyaros, also locally known as Gioura, is an arid, unpopulated, and uninhabited Greek island in the northern Cyclades near the islands of Andros and Tinos, with an area of 23 square kilometres (9 sq mi). It is a part of the municipality of Ano Syros, which lies primarily on the island of Syros. This and other small islands of the Aegean Sea served as places of exile for important persons in the early Roman empire. The extremity of its desolation was proverbial among Roman authors, such as Tacitus and Juvenal. It was a place of exile for left-wing political dissidents in Greece from 1948 until 1974. During that time, at least 22,000 people were exiled or imprisoned on the island. It is an island of great ecological importance as it hosts the largest population of monk seals in the Mediterranean.

The Cyclades are an island group in the Aegean Sea, southeast of mainland Greece and a former administrative prefecture of Greece. They are one of the island groups which constitute the Aegean archipelago. The name refers to the archipelago forming a circle around the sacred island of Delos. The largest island of the Cyclades is Naxos, however the most populated is Syros.