Castlereagh ( ) may refer to:
==People== Marquess of Londonderry, subsidiary title Viscount Castlereagh, used as courtesy title for the Marquess's eldest son; in particular Robert Stewart, Viscount Castlereagh (1769–1822), later 2nd Marquess of Londonderry: Anglo-Irish statesman and British Foreign Secretary.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).