The Bangor-class minesweepers were a class of minesweepers operated by the Royal Navy (RN), and other Commonwealth countries during World War II. The design dated from the Treaty restriction that 600 ton ships had no restriction on building numbers. The RN's first trial with the 600 ton displacement were the Kingfisher class sloops/corvettes. The Kingfisher class were horrible, incurable topweight restrictions, made them almost useless as escorts. They virtually needed escorts themselves.

With the clouds of war gathering on the horizon, a new design of escort of 600 tons was promulgated that could be speedily built in time of war. Thus was born the Bangor class. The need for fast construction coupled with the limitations of engineering resources resulted in several variations existing based on the availability of propulsion machinery. They all had twin screws, but the machinery was a mix of steam turbine, slow-speed steam reciprocating, high-speed steam reciprocating, and diesel. Displacement varied with propulsion machinery from 600 to 670 tons. The reciprocating engine powered type were the Bangor class, the diesel engined version were known as the Blyth class and the steam turbined ones as the Ardrossan class. The New Zealand navy built ships were the Bird class. The Australis equivalent was the bigger Latrobe Class.

The ships were to be inshore escorts and minesweepers, ideal for around the coasts of Great Britain, the Mediterranean, Caribbean, and other coastal areas. They were not built for the open seas of the major oceans. But as with the other escorts, they ended up serving everywhere in WW2, from the Atlantic and Arctic to the wide open Pacific ocean. A New Zealand pair of these vessels (HMNZS Kiwi and Moa) sank one of the huge aircraft carrying submarines of the Japanese - I-1.