The Mongolian Death Worm is a cryptid purported to exist in the Gobi Desert. It is generally considered a cryptozoological creature; one whose sightings and reports are disputed or unconfirmed.

It is described as a bright red worm with a wide body that is 0.6 to 1.5 meters (2 to 5 feet) long.[citation needed]

In general, scientists reject the possibility that such mega-fauna cryptids exist, because of the improbably large numbers necessary to maintain a breeding population and because climate and food supply issues make their survival in reported habitats unlikely.

The local name is allghoi (or orghoi) khorkhoy (хорхой), which means "blood filled intestine worm" because it is reported to look like the intestine of a cow. It is the subject of a number of extraordinary claims by Mongolian locals—such as the ability of the worm to spew forth sulfuric acid that, on contact, will turn anything it touches yellow and corroded (which would kill a human), and its purported ability to kill at a distance by means of electric discharge.

One investigator of that animal is Czech author Ivan Mackerle, who said in Fate Magazine (June 1991) that it reportedly kills its victims by electrocution. British zoologist Karl Shuker brought it to the general attention of the English speaking public in his 1996 book The Unexplained, followed a year later by his Fortean Studies paper on this subject, which was reprinted in The Beasts That Hide From Man in which it was hypothesized that the death worm was an Amphisbaenid. Loren Coleman also included this animal in Cryptozoology A to Z.

A joint expedition in 2005 by the Centre for Fortean Zoology and E-Mongol investigated new reports and sighting of the creature. They found no evidence of its existence, but could not rule out that it might live in the deep Gobi Desert along the prohibited areas of the Mongolian/Chinese border.

The most recent expedition was in 2006–2007, conducted by the reality-television series, Destination Truth.