Necrophidius
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The Necrophidius which is Greeky-geeky sciencey jargon for "Death Worm" is a bone-golem raised from a giant snake skeleton and a human skull. Its bite can cause paralysis but magical paralysis - not venomous. It can further do a snake dance to hypnotise opponents. It has "Average" intelligence so may be employed for assassinations.
This was the best monster submitted to Fiend Factory up to White Dwarf issue #15, if you asked its readers, which those editors did. Simon Tilbrook submitted it, which made it to #7, in time for Fiend Folio to recognise its awesome and include it. The Tome of Horrors gave them a 3e makeover.
White Dwarf #25 would post a "Guardian" variant: its spirit can leave its body and animate its petrified victims, one at a time. In its own body, it regenerates. Even more awesome; but TSR - burned by the dross in the 'Factory up to #13 - was ignoring those submissions so missed this one.
2nd Edition's Monstrous Compendium Annual Volume 1 has an identical looking creature called a Bone Naga, that is not a golem but a "created undead". From 3e onward this twin monster supplanted the necrophidius as head bone snake. While the necrophidius's last official appearance was in the 3e Fiend Folio, the bone naga has appeared in 3e's second Monster Manual and the first Monster Manuals of 4e and 5e.
Gallery
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1e
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2e
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3e
Bone Naga
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2e
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3e
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5e