| Brosnahan Island | |
| Map: | Antarctica |
| Location: | Antarctica |
| Population: | Uninhabited |
| Country: | None |
| Treaty System: | Antarctic Treaty System |
Brosnahan Island is an island 10NaN0 long, rising above the western part of the Ross Ice Shelf 11nmi northeast of Cape Murray. It was mapped by the United States Geological Survey from tellurometer surveys and Navy air photos, 1959–63, and named by the Advisory Committee on Antarctic Names for Commander James J. Brosnahan, U.S. Navy, commander of the McMurdo Station winter party, 1961.