Allegany is an unincorporated community in Coos County, Oregon, United States. It lies at the upstream end of the Millicoma River, where the East Fork Millicoma River and West Fork Millicoma River join to form the main stem, a short tributary of the Coos River. Oregon Route 241 passes through Allegany. The community borders the Elliott State Forest.
A post office was established at Allegany in 1893, and it is unknown why this spelling was chosen. Allegany is used for several geographic features in the state of New York, while Allegheny is the preferred spelling in Pennsylvania.
The Golden and Silver Falls State Natural Area is a state park northeast of Allegany. It features two 100-foot (30 m) waterfalls in an old-growth forest setting.