HMNZS Achilles was a Leander-class light cruiser which served with the Royal New Zealand Navy in the Second World War, the second of five in the class. Originally constructed by the Royal Navy, she was loaned to New Zealand in 1936 before formally joining the new Royal New Zealand Navy in 1941. She became famous for her part in the Battle of the River Plate, alongside HMS Ajax and HMS Exeter and notable for being the first Royal Navy cruiser to have fire control radar, with the installation of the New Zealand-made SS1 fire-control radar in June 1940.