The Blue Petrel (Halobaena caerulea) is a small seabird in the family Procellariidae. This small petrel is the only member of the genus Halobaena but is closely allied to the prions. Its plumage, which is white on the underside of the body and grey with the distinct M banding across the uppersides resembles the prions; it differs from them by its smaller bill and the distinctive white tip to its tail. They have a circumpolar distribution, breeding near the Antarctic Polar Front.

Like all procellariids the Blue Petrels are colonial, nesting in large colonies which are visited at night to avoid being taken by skuas. Blue petrels lay a single egg in a nest inside a burrow. Both parents incubate the egg for around 50 days. After hatching the chick takes around 55 days to fledge. Their colonies can be found on Marion Island and Prince Edward Island-(of the Prince Edward Islands), the Crozet Islands, the Kerguelen archipelago, Macquarie Island and South Georgia. At sea they range widely from Australia to South Africa, South America and Antarctica. They feed mostly on euphausiid shrimp, also taking other crustaceans and fish and squid, which they can dive for to at least 6 metres.