Carthus Sand Worm

The Sand Worm is an enemy in Dark Souls III

Description
One of the largest monsters in Lothric; the Sand Worm is enormous, and covered in a rock-like shell. Despite its large size, it can move extremely quickly.

The Sand Worm is a formidable opponent, using a lightning beam to take out targets at a distance, and while the protrusions on its shell are combined with its rapid movements to deal with to melee attackers.

Location
Smouldering Lake - Located a short distance before the Old Demon King fight. It is initially burrowed, but appears as the player closes in on the area.

Lore
At some point, the Sand Worm attacked the Catacombs of Carthus, but was repelled by the grave wardens. It then dominated the Smouldering Lake, which became its new home.