Ambull
Native to the death world of Luther McIntyre, the Ambull is a large ape-shaped subterranean desert-dwelling beast. It excavates tunnels with iron-hard claws and devours other cave-dwelling creatures with its expandable jaws. The Ambull has been spread across the Imperium by well-meaning Magos Biologis of the Adeptus Mechanicus in attempts at domestication (apparently they taste delicious when properly cooked) however these guys were having absolutely none of it and just tunneled the fuck around, mincing anything that they disliked and generally becoming a pest on any world they end up infesting.
From the description of the Ambull's physical appearance, and their knack for tunneling, there's a certain resemblance to the Umber Hulk, a Dungeons & Dragons monster that predates the creation of 40k.
On Necromunda, they apparently like to make robotic versions of the Ambull called Ambots, though whether these are bionically enhanced Ambulls, or some insane tinkerer’s attempt to create an entirely artificial analogue for Ambulls is unclear.
Tabletop
In 2019 the Ambull will finally be coming to the tabletop, in both regular and robotic varieties, via expansions to Blackstone Fortress and Necromunda respectively.
