Lich

Liches are a class of monster in NetHack represented by the overall symbol. They are all powerful spell-casters, and their more powerful forms have the ability to destroy armor, cast touch of death and most other spells, and teleport away when attacked; they are thus a frequent target of blessed genocide. All liches crumble to dust when killed and therefore do not leave corpses.

The lich, is also the least powerful monster of this class. It is slower than its brethren and not a significant threat. At the experience levels it is normally encountered, its complement of spells include healing itself, hasting itself, stunning you, turning invisible, draining your strength, destroying your armor, and cursing your items.

Other liches include demiliches, master liches, and arch-liches.

Encyclopedia entry
But on its heels ere the sunset faded, there came a second apparition, striding with incredible strides and halting when it loomed almost upon me in the red twilight-the monstrous mummy of some ancient king still crowned with untarnished gold but turning to my gaze a visage that more than time or the worm had wasted. Broken swathings flapped about the skeleton legs, and above the crown that was set with sapphires and orange rubies, a black something swayed and nodded horribly; but, for an instant, I did not dream what it was. Then, in its middle, two oblique and scarlet eyes opened and glowed like hellish coals, and two ophidian fangs glittered in an ape-like mouth. A squat, furless, shapeless head on a neck of disproportionate extent leaned unspeakably down and whispered in the mummy's ear. Then, with one stride, the titanic lich took half the distance between us, and from out the folds of the tattered sere-cloth a gaunt arm arose, and fleshless, taloned fingers laden with glowering gems, reached out and fumbled for my throat. . .        [ The Abominations of Yondo, Clark Ashton Smith, 1926 ]