Duke of Eorle
A member of the Ankh-Morporkian nobility, who appears as a supporting character in several scenes, such as the dinner party Sybil Ramkin throws to introduce her new husband to the social level he will be expected to mix in following marriage and his retirement as Watch Captain. (Men at Arms)The Duke distinguishes himself here by a succession of small-minded, prejudiced and self-contradictory remarks about trolls and dwarfs, of the sort that have Samuel Vimes contemplating taking a wine bottle by the neck out of a reason other than to pour a guest a drink.
Eorle also appears as one of the nobility invited by Edward d'Eath to witness a slide presentation (not a million miles away from what we on Roundworld might call "Powerpoint", incidentally) designed to establish, beyond all possible doubt, the right to the throne of one Carrot Ironfoundersson. Here, he finds sudden reasons not to want to upset the status quo that keeps Vetinari firmly atop the heap. Eorle is a small-minded snobbish reactionary, but has enough cunning and resources to live in the manner accustomed. In times of crisis he is affluent enough to raise a Regiment for the city.
Æorle, or Eœrle, is the Anglo-Saxon original spelling of the title "Earl". Therefore "Duke of Eorle" is something of a tautology, unless there is a place called Eorle somewhere on the Discworld.
And, of course, there was a 1960's song by Gene Chandler, among others...