Ancasta was a Celtic goddess worshipped in Roman Britain. She is known from a single dedicatory inscription found in the United Kingdom at the Roman settlement of Clausentum (Bitterne, near Southampton). Ancasta may be taken to be a local goddess, possibly associated with the nearby River Itchen.
The votive dedication to Ancasta reads:
It may be possible that the name 'Ancasta' is related to Proto-Celtic *kasto- meaning 'swift'.
The inscription is now in the SeaCity Museum.