The Mongolian death worm (Mongolian: олгой-хорхой, olgoi-khorkhoi, "large intestine worm") is a creature alleged to exist in the Gobi Desert.
The creature first came to Western attention as a result of Roy Chapman Andrews's 1926 book On the Trail of Ancient Man. The American paleontologist described second-hand tales of the monster that he heard at a gathering of Mongolian officials: "None of those present ever had seen the creature, but they all firmly believed in its existence and described it minutely."