Annex or Annexe may refer to:

• annexation, the legal incorporation of some territory into another geo-political entity
• annex, a building that is an addition to another building
• annex, a document that adds onto another document
• The Annex, a neighbourhood in Toronto, Canada
• The Annexe, the name of Anne Frank's hiding place in Amsterdam
• In computer engineering: a type of Serial console server or Terminal server device

Annex may also refer to:

• The Classical Annex, a short story by E. M. Forster