Ethir may refer to:
- the Sindarin term for a Scout or Spy. Literally it's a "Lookout" or "Watcher". For example: Amon Ethir (the Spyhill) in Beleriand.
- the Sindarin term for the mouth or delta or estuary of a river, e.g.: Ethir Anduin; Ethir Baranduin; Ethir Gwathló; Ethir Harnen
- Ethir (Settlement), a small settlement in Ethir Anduin in Gondor.