The King Brown, Mulga Snake or Pilbara Cobra, is a species of venomous snake found in Australia. It is one of the longest venomous snakes in the world and the second longest in Australia. Despite one of its common names, "king brown", it is part of the Pseudechis (black snake) genus.

Mulga snakes are large, venomous snakes growing up to 2.5 to 3.0 m (8.2 to 9.8 ft) in length in the largest specimens, although 1.5 m (4.9 ft) is a more typical length for an average adult. It is exceeded in length amongst venomous snakes only by the Asiatic king cobra, some species of African mambas, the Australian taipan, and genus Lachesis (bushmasters) of the American neotropics. A good-sized adult mulga snake of 2 to 2.5 m (6.6 to 8.2 ft) length can scale 3 to 6 kg (6.6 to 13 lb) and it often scales heavier than the co-occurring taipans. Depending on its areal extent, mulga snakes can be of a light brown colour in the desert to a dark brown-blackish colour in the cooler regions of Queensland, South Australia and New South Wales. Mulga snakes are robust, with a wide heads and smooth snouts.

The mulga snake venom consists of neurotoxin. The LD50 is 2.38 mg/kg subcutaneous. Its venom is not particularly toxic to mice, but it is produced in huge quantities. The average tiger snake produces around 10–40 mg when milked. By comparison, a large king brown snake may deliver 150 mg in one bite.

Black snake antivenom is used to treat bites from this species, after a CSL venom detection kit has returned a conclusive result for mulga snake envenomation, and there are signs that antivenom use is required.

Female mulga snakes produce a clutch of around 8–20 eggs, which may be laid in a disused burrow or beneath a log or rock. There is no maternal care for the eggs once they have been laid. Eggs take about 2–3 months to hatch, after which time the newly hatched snakes must care for themselves.

Mulga snakes occur in most states of Australia except for Victoria and Tasmania. Its range includes all of the Northern Territory, most parts of Western Australia, Queensland, New South Wales and South Australia. It may also be found in the western parts of the Australian Capital Territory. Mulga snakes inhabit woodlands, hummock grasslands, chenopod scrublands and almost bare gibber or sandy deserts, usually sheltering near humans under timber, rubbish piles, burrows and deep soil cracks. They are not found in rainforests.

The mulga snake primarily preys on lizards, birds, mammals and frogs. It is well adapted to eating other snakes, including all venomous snakes.