Kea, also known as Gia or Tzia, Zea, and, in antiquity, Keos, is a Greek island in the Cyclades archipelago in the Aegean Sea. Kea is part of the Kea-Kythnos regional unit. Its capital, Ioulis, is inland at a high altitude (like most ancient Cycladic settlements, for fear of pirates) and is considered quite picturesque. Other major villages of Kea are the port of Korissia and the fishing village of Vourkari. After suffering depopulation for many decades, Kea has been recently rediscovered by Athens as a convenient destination for weekends and yachting trips. The population in 2011 was 2,455.

It is the island of the Cyclades complex that is closest to Attica (about 1 hour by ferry from Lavrio) and is also 20 km (12 mi) from Cape Sounio as well as 60 km (37 mi) SE of Athens. Its climate is arid, and its terrain is hilly. Kea is 19 km (12 mi) long from north to south and 9 km (6 mi) wide from west to east. The area is 129 km2 (50 sq mi) with the highest point being 560 m (1,837 ft) above sea level

The municipality Kea includes the island of Makronisos to the northwest.