Professor of Recondite Architecture and Origami Map Folding
A rather useful Wizard residing at Unseen University, in his job as "an expert at finding an expert". His specialty in Recondite Architecture (obscure/hidden architecture) means that he is quite possibly the only person who understands the convoluted bent dimensions of the university. And his prowess in Origami Map Folding makes him capable of constructing a map of the University (admittedly one that looks like an exploding chrysanthemum) that would probably be accurate for the next few days... then you would need to track him down again and have him make another one...
Potentially very useful to the Archchancellor, when a specialist needs to be found in a hurry. For instance, in The Last Continent, while Ridcully has never met him before, he manages to produce a map leading the senior wizards to the room of the Egregious Professor of Cruel and Unusual Geography.