While the king cobra (Ophiophagus hannah) generally takes shelter in animal burrows, under fallen trees, and among rock formations, females make specialized nests for their eggs and sometimes guard them for months at a time. The mothers-to-be don't eat the entire time they're guarding the nest and are unusually aggressive, lashing out at pretty much anything that comes close.

They prey chiefly on other snakes, such as Asian rat snakes, dhamans, pythons, and even smaller cobras. But when food is scarce, they will dine on other vertebrates, such as lizards and rodents.

Despite their common name, king cobras are not classified as true cobras, which belong to the genus Naja. The king cobra is the sole member the genus Ophiophagus, and genetic evidence suggests that these big snakes are more closely related to the mambas of sub-Saharan Africa than to true cobras.

Adult king cobras are 3.18 to 4 m (10.4 to 13.1 ft) long on average, making them the world's longest venomous snakes. But the longest known individual measured in at a monstrous 5.85 m (19.2 ft).

The king cobra possesses a potent neurotoxic venom, and death can occur in as little as 30 minutes after being bitten.

The toxins affect the victim's central nervous system, resulting in severe pain, blurred vision, vertigo, drowsiness, and eventually paralysis. If the envenomation is serious, it progresses to cardiovascular collapse, and the victim falls into a coma. Death soon follows due to respiratory failure.

The venom of hatchlings is just as potent as that of the adults.

In Thailand, a concoction of turmeric root is believed to create a strong resistance to the venom of the king cobra when ingested.

Like other snakes, king cobras smell using the tip of their tongue, and a forked tongue allows them to sense from which direction a smell is coming.

While the hisses of most snakes are of a broad-frequency span ranging from roughly 3,000 to 13,000 Hz with a dominant frequency near 7,500 Hz, a king cobra hiss (sometimes described as a "growl") consists solely of frequencies below 2,500 Hz, with a dominant frequency near 600 Hz, a much lower-sounding frequency closer to that of a human voice.