Catoblepas 1977 AD&D MM

This nightmare creature is loathsome beyond description and has no redeeming features. Its body resembles that of a huge, bloated buffalo and gives off an offensive odor. The catoblepas' neck is long and thin, and perched atop it is a big head uglier than that of a warthog. Its legs are thick and stumpy, much like a hippopotamus. The creature's tail is strong and snakey, however, and moves with amazing swiftness to strike enemies. Any creature so struck has a base 75% chance of being stunned for 1-10 melee rounds; the base chance being modified by adjustment downward by 5% for every level (or hit die for monsters) above 1. Thus, if an 11th level character is struck by the tail there is only a 25% chance of stunning. Perhaps its habitat - fetid swamps and miasmal marshes - cause the bizarre combination of genetic characteristics in this monster, or perhaps it was due to some ghastly tinkering with life by a demented godling. In any case, the most horrid aspect of the catoblepas is its bloodshot eyes.

The gaze of the catoblepas is equal to a death ray, extending 6" from the eyes (even into the astral and ethereal planes). Any creature which meets this gaze dies without any chance to save itself. Complete surprise (a 2 on 6-sided die) means one of the party encountering the monster has met its gaze. Otherwise, the very weak neck of the catoblepas has a 25% chance of raising the head high enough to use its eyes. If both parties are sill this chance increases by 15% per melee round, If the monster must follow quick movements, or if it is shambling along in pursuit of prey, there is only a 10% chance per melee round of the neck raising the head sufficiently high to fix its gaze. A fleeing victim, even with eyes averted, is subject to the deadly effect of the catoblepas' eyes, although there is a saving throw.