Tommyknockers infest mines where they cause trouble by stealing or sabotaging operations. These mischievous little people stand only two feet tall, with big heads, long arms, wrinkled faces and white beards. They possess the thief-like abilities of Move Silently and Hide using a 75% success rate, which allows them to move about a mine undetected. They are master pickpockets, succeeding 99% of the time.

Tommyknockers have a mischievous nature that drives them to sneak up on unsuspecting adventurers to steal small items from pockets or backpacks. They may also spill containers or damage machines, such as dropping pebbles into gears. But for all the distress they cause, miners can appreciate one beneficial quality of the tommyknocker: the habit of tapping to communicate a level of danger. Out of sight, the little fellows tap out a rhythm that increases in tempo as those they ogle approach danger.