This hunched creature has a single huge eye that dominates its entire face. Its body is bloated and misshappen, and its limbs are wiry but strong, Its arms end in claws that reach the ground as it moves in awkward hop.
Source: Miniatures Handbook 3.5
D&D Monster Manual 5E
Nothic are aberrations that live in underground lairs and ruins. Rumor has it that wizards who dabble in the arcane secrets are transformed into a Nothic when a rituals goes wrong. The Nothic retain no memory of their former selves. They do have an urge to seek out magic. They can be encountered lurking in cellars of the local arcane academy or ruins of a great wizards tower.
The Nothic seek forbidden lore and knowledge. They covet magic items and will easily accept them as payment for lore they may possess. The Nothic hope that one day their desire for magical secrets will revert their condition.
Combat: In D&D 3.5 the Nothic is a CR 3 creature. It has relatively high hit points that average out at 42. They have two claw attacks that deal 1d4+4 damage.
-Flesh Rotting Gaze: Anyone who see a Nothic within 30ft must make a Will Save 16 or take 1d6 points of damage.
-Sight: Nothic can see invisibility and have darkvision 120ft.
In D&D 5E the Nothic is a Challenge Rating of 2. It has 45 hit points, Armor Class of 15, and two claw attacks that deal 1d6+3 damage.
Rotting Gaze: The Nothic can target one creature with it's gaze within 30ft. The victim must make a DC 12 Constitution Saving Throw or take 3d6 necrotic damage.
Weird Insight: The Nothic can target a creature within 30ft to steal a piece of knowledge from them. It's a contest between the victims Charisma(Deception) vs the Nothics Wisdom(Insight). Failure allows that Nothic to steal one fact or secret from the victim.
The Miniatures Handbook version is pretty sparse about the Nothic. It mentions nothing about their arcane past and has them as simple subterranean lurkers. The D&D 5E Monster Manual gives them some backstory and depth. I like the Weird Insight ability of the Nothic for 5E. Stealing a Secret from a prominent NPC can lead to an interesting sidetrek.