Hisøya or Hisøy (historically: Hisøen) is an island in Agder county, Norway.

In 2015, the island was home to about 4,450 people giving it a population density of about 550 inhabitants per square kilometre (1,400/sq mi).

[1] The 8.1-square-kilometre (3.1 sq mi) island lies along the Skaggerak coast of southeastern Norway.

The island of Tromøya lies to the northeast, separated from Hisøya by the Galtesundet strait.

The small islands of Ærøya, Havsøya, and Merdø lie just to the southeast of Hisøya.