HMS Tamar is a Batch 2 River-class offshore patrol vessel of the Royal Navy. Named after the River Tamar in England, this is the seventh Royal Navy ship to be named Tamar. She is the fourth Batch 2 River-class vessel to be built and is forward deployed long-term to the Indo-Pacific region with her sister ship HMS Spey.

The River class is a class of offshore patrol vessels built primarily for the Royal Navy of the United Kingdom. A total of nine were built for the Royal Navy (RN), four Batch 1 and five Batch 2. One Batch 1 (HMS Clyde), which was the Falklands guard ship, was decommissioned and transferred at the end of its lease to the Royal Bahrain Naval Force.