Kostilka Island (Bulgarian: остров Костилка, romanized: ostrov Kostilka, IPA: [ˈɔstrof kosˈtiɫkɐ]) is the rocky island 213 m long in west–east direction and 137 m wide in the Myriad Islands group of Wilhelm Archipelago in the Antarctic Peninsula region.

[1] The feature is so named because of its shape supposedly resembling a fruit's stone ('kostilka' in Bulgarian), and in association with other descriptive names of islands in the area.

[1] Kostilka Island is located at 65°05′57″S 64°24′52″W / 65.09917°S 64.41444°W / -65.09917; -64.41444, which is 3.35 km northwest of Flank Island, 3.47 km southeast of Final Island, and 6.74 km west-northwest of Vedel Islands.

This article includes information from the Antarctic Place-names Commission of Bulgaria which is used with permission.

This Wilhelm Archipelago location article is a stub.