Oia is a community on the islands of Thira (Santorini) and Therasia, in the Cyclades, Greece. The population was 1,230 inhabitants at the 2001 census, and the land area is 19.449 km². The population and land area are distributed as follows: 962 persons on 10.150 km² in Santorini, and 268 persons on 9.299 km² in Therasia. The community shares the island of Thira with the Municipality of Thira (Santorini), and is centered in the northwesternmost part of the island.