Machias may refer to:

• Machias, Maine, a New England town
  • Machias (CDP), Maine, the main village within the town
• Machias Bay, in Washington County, Maine
• Machias River (Aroostook River tributary) in northern Maine
• Machias River in eastern Maine
• Machias Seal Island, an island in the Gulf of Maine
• Machias, New York, a town
  • Machias (CDP), New York, the main hamlet within the town
• Machias, Washington, a census-designated place

• USS Machias, the name of more than one United States Navy ship