Mrs. Duffel is Dennis the Menace's teacher who works with the villains, Olive, Cuthbert Cringeworthy, Teacher, Headmaster, Janitor, Winston, Slasher Brown, Slasher Brown's Henchmen, Mr. Abercrombie, The Colonel, The Inspector, Captain Prefab, Clint Katzenberger, Sergeant Slipper, Hugo Trenchfoot, Vilhemina Slop Bucket, Mrs. Greature, Mrs. Creecher, Fatty Fudge, Reg Trademark, Captain Trout, Sergeant Boot and Sir Fitz-Patrick Flush. She is voiced by Prunella Scales.