HMS Alligator was a 28-gun Atholl-class sixth rate of the Royal Navy. She was launched at Cochin, British India on 29 March 1821. Alligator, under the command of Captain Lambert, operated in New Zealand during 1834, leaving on 31 March 1834, but returned again in September the same year to rescue the crew and passengers of Harriet, which was wrecked near Cape Egmont, Taranaki and were held by the Ngāti Ruanui. In March 1834, Alligator, was on hand (and fired the 13-gun salute) at the first hoisting of the first national flag of New Zealand, at Waitangi, Bay of Islands.