| Masteyra Island | |
| Map: | Antarctica |
| Map Relief: | yes |
| Location: | Antarctica |
| Coordinates: | -64.3756°N -63.6964°W |
| Archipelago: | Palmer Archipelago |
| Length M: | 700 |
| Width M: | 200 |
| Population: | Uninhabited |
| Country: | None |
| Treaty System: | Antarctic Treaty System |
Masteyra Island (bg|остров Мастейра|ostrov Masteyra, pronounced as /bg/) is a rocky island 700 m long in east-west direction and 200 m wide lying in Perrier Bay on the northwest coast of Anvers Island in the Palmer Archipelago, Antarctica. It is separated from Anvers Island to the east-southeast by a 1.13 km wide passage.
The island is named after the ancient Thracian settlement and fortress of Masteyra in Southern Bulgaria.
Masteyra Island is located at -64.3756°N -63.6964°W, 6.58 km south of Quinton Point, 4.21 km north of Vromos Island and 7.55 km east-northeast of Giard Point. British mapping in 1980.