Greetling
After Geoffrey, the Chief Butt of the Fools' Guild, Master Greetling is quite possibly the second most ill-adjusted, neurotic, neurovorous, Guild leader in Ankh-Morpork. He trembles and gibbers a lot, he is prone to the shakes, is certainly upset by sudden unexpected loud noises, and quite often needs to be led away by kindly hands, perhaps in the direction of the old Dried Frog Pills.
Master Greetling is, of course, head of the Teachers' Guild.