The Red-bellied Black Snake is a species of elapid snake native to eastern Australia. Though its venom is capable of causing significant morbidity, a bite from it is not generally fatal and less venomous than other deadly Australian snakes. It is common in woodlands, forests and swamplands of eastern Australia. It is one of Australia's best-known snakes, as it is common in urban areas along the eastern coast of Australia. It can be found in the urban forest, woodland, plains and bushland areas of Canberra, Sydney, Brisbane, Melbourne, Cairns and Adelaide. It is most commonly seen close to dams, streams, billabongs and other bodies of water.

It has an average total length of 1.5 to 2 metres.

The Red-bellied Black Snake is glossy black on the dorsal surface and red, crimson or pink in colour on the lower sides and belly. The snout is often a lighter brown colour. It is a relatively large species of snake reaching up to two metres in length, although an average sized specimen would be closer to 1.4 m. Like all Elapid snakes it is front fanged.

This is generally not an aggressive species. However, when provoked, it will recoil into its striking stance as a threat, but will try to escape at the first opportunity. It is most active by day. When not hunting or basking it may be found beneath timber, rocks and rubbish or down holes and burrows.

The Red-bellied Black Snake's diet consists primarily of frogs, but it also preys on reptiles and small mammals. They also eat other snakes, including those of their own species.

Red-bellied Black Snake venom consists of neurotoxins, myotoxins, coagulants and also has haemolytic properties. Bites from Red-bellied Black Snakes are rarely life-threatening due to the snake usually choosing to inject little venom toxin, but are still in need of immediate medical attention. Tiger Snake antivenom is used to treat bites. While black snake antivenom can be used, tiger snake antivenom can be used at a lower dose. The smaller dose is cheaper to produce, and is less likely to cause a reaction in the patient.

Red-bellied Black Snakes are ovoviviparous; that is, they give birth to live young in individual membranous sacs. The young, numbering between eight and 40, emerge from their sacs very shortly after birth, and have an average length of about 122 mm. In the wild, few will survive to reproduce.