A fairly-high-level monster in Nethack represented by a red x. Their distinguishing feature is that they can prick your leg. The most noticeable effect of having your leg injured in this fashion is that you can become burdened. You also cannot kick things.
The pricking attack may also permanently decrease your strength.
While nothing besides a lump of royal jelly or non-cursed potion of speed or will make your legs heal faster, any permanent strength reductions can be fixed by a unicorn horn, or spell / potion of restore ability. Wearing boots usually protects your legs, but not always. Levitating keeps you out of its reach completely.