Skimmer appeared in The Fifth Elephant. One of Lord Vetinari's clerks, he was sent along with Commander Sir Samuel Vimes, who was made Ambassador to Uberwald, to handle the more delicate and financial side of things while Vimes handed round cucumber sandwiches.
Skimmer was slim, with a somewhat oddly-shaped head (it looked as if someone had squeezed the bottom half and forced everything into the top). He was balding and in the habit of teasing what remained of his hair over the top of his head. It was difficult to tell his age - Vimes observed that he could be twenty-five and a worrier, or a fresh-faced forty. Vimes was inclined to the former - Skimmer had the look of someone who watched the world over the top of a book.
He also had an odd verbal tic - adding "Mhm-mhm" or some variation of it to the ends of sentences or where others would say "...er..."
This harmless exterior cloaked a mind like a trap and the abilities of a scholarship boy from the Assassins' School, as the bandits who tried to capture Sir Samuel's coaches on the way to Uberwald discovered, much to their dismay. Skimmer's personal arsenal included a palm dagger, a highly-illegal one-shot crossbow, blades in his shoes, and a razor-edged hat. Unfortunately, he underestimated his opponents and came to a rather unpleasant, and, I feel, undeserved end. His body was subsequently used in an attempt to frame Ankh-Morpork for trying to assassinate the Dwarves' Low King.