Donousa (Greek: Δονούσα, also Δενούσα - Denousa) is an island and a former community in the Cyclades, Greece. Since the 2011 local government reform it is part of the municipality Naxos and Lesser Cyclades, of which it is a municipal unit. Donousa is the easternmost island of the Lesser Cyclades.
Donousa is located about 25 km (13 nmi) north of Amorgos and 7 kilometres (4 nmi) from the Makaries islands as well as 15 kilometres (9 miles) east of the island of Naxos. The area is only 13.75 square kilometres (5.31 sq mi) and is composed of mountains, hills, rocks and some bushes. It has a diameter of 5 km (3 mi) with the highest point being 363 metres (1,191 ft) and with only 163 inhabitants. Donousa has a small port at Stavros, its main settlement, having ferry routes to Naxos and Amorgos. Other villages include Mersini (on the southeastern coast) and Kalotaritissa (near its northern coastline).
The population was 235 in 1928, 250 in 1946 and the population today has declined to only 163 (2001 census). The later years saw the island rise in tourism which has visitors heading to and from Naxos and Amorgos.