Forrester Island Wilderness, Protected wilderness area in Southeast Alaska, United States.

Forrester Island Wilderness is a 2,832-acre (1,146 ha) protected area on Forrester Island, 20 miles (32 km) west of Dall Island in the Prince of Wales-Hyder Census Area. The island is 5.2 miles (8.4 km) long, covers 3.97 sq mi (10.29 km2) and rises 814 feet (248 m). It is wooded and mountainous, part of the Gulf of Alaska unit of the Alaska Maritime National Wildlife Refuge.

The site was named by George Dixon in 1787 and protected by President William Howard Taft in 1912. The designation came as part of a broader conservation effort for several islands in the region.

The place keeps its natural character through rules that ban motorized equipment and mechanical transport. Visitors experience the unspoiled landscape only on foot or by traditional boat.

The island lies 20 miles (32 km) west of Dall Island, in the Prince of Wales-Hyder Census Area, and is reached only by boat or floatplane. It is part of the Gulf of Alaska unit of the Alaska Maritime National Wildlife Refuge, and the 2,832-acre wilderness has no trails or facilities. Landing is on a wooded, mountainous shore rising to 814 feet (248 m).

Forrester Island hosts rookeries of Steller sea lions. One individual was recorded migrating 1,600 miles (2,600 km) between Forrester Island and Cape Newenham in Bristol Bay, the longest migration known for the species. The island's Haida name is Gasḵúu.