The "Grave Digger" was a mutated arthropod that dramatically increased in size after being exposed to the t-virus in Raccoon City. It resembles an enormous worm or grub. 1
History
Due to the waste products from the Raccoon City Underground Laboratory superseding the threshold of the Incineration Disposal Plant, a large amount of contamination seeped into the nearby ground. Infected bodies were also disposed of near the facility, leading to a number of arthropods feasting on the remains, causing a huge, sudden mutation within some of them. 2
At least two of these creatures were reported during the outbreak and grew to an enormous size after feeding off infected bodies that were disposed of by researchers. One was an adult that had recently shed its skin and was colored white whilst the second was a fully grown specimen with a dark brown complexion. The Grave Digger later inspired Umbrella researchers to develop the Gulp Worm B.O.W. after being observed in Raccoon City. 3 4
Attributes
These organisms preferred to stay underground in dark, damp places and had created vast tunnels underneath the city streets. The second recorded specimen made its habitat beneath the Raccoon City cemetery, where it feasted on the dead flesh of the corpses. After sensing prey, the creature could sense their distance and rush to the surface. The length of the creature was estimated at around 10 meters. One effect of the t-virus is the growth of large powerful jaws which can chew right through concrete, and its vastly improved digestive system enables it to swallow a human being whole. Both specimens recorded during the incident maintained a high tolerance for damage, with the second more mature specimen having the highest tolerance.
Etymology
The name of this creature is derived from the second specimen. After being recorded by Umbrella, they dubbed it the "Grave Digger" based on its habitat and tendency to eat corpses underground.