Mrs. Whitlow is Unseen University's Head of Housekeeping. She is very modest (to the point of not wanting to show her ankles), but also be quite forthright and direct when necessary (eg, when explaining sex to the God of Evolution in The Last Continent). She has often lost her prudish streak. When overcome by music with rocks in, she threw her undergarments onto the stage in Soul Music and when bathing alone on the island in The Last Continent she removed her corsets.
She is pleasant and friendly to the wizards, but can be sharp and surly to her staff. We learn in Equal Rites that she has outlasted four husbands, and is actively hunting for Number Five.
As noted about the young and naive Sacharissa Cripslock, she makes the fundamental error of confusing mannerisms with manners, and thinks good breeding and etiquette go hand-in-hand. She therefore has mixed feelings about Mustrum Ridcully, who, in Moving Pictures, offends her sensibilities in the course of a delicate discussion concerning vases spitting at a member of her staff, a much put-upon maid called Ksandra. What she delicately terms "Hexpectorating" (a pun on "hex" and "expectorate") is interpreted by Ridcully as "Oh, can't have that, vases gobbin' over people". Mrs Whitlow is a mistress of the unnecessary aspirant, often putting in an additional "H" at the start of words, as it sounds posher.
Her housekeeping abilities amaze the wizards, and even Mustrum Ridcully is somewhat in awe of her: in 'Hogfather', he hesitates to enter the laundry until he learns that Mrs. Whitlow is away.
She plays a minor role in most books, but a major role in The Last Continent, when she is accidentally trapped with the wizards on a primitive island thousands of years in the past (she thinks this is a prank the wizards are playing). Some of the wizards (including the Dean, but particularly the Senior Wrangler) show a strong tendency to obsess over Mrs Whitlow throughout the novel. The entire University group find themselves accidentally rejuvenated by temporal fluxes during their stay on the island. Unlike the Wizards, whose morphic fields correct themselves back to old (or middle) age, Mrs. Whitlow never reverts from her youthful appearance, suggesting that at her core she remains youthful. This idea also occurs in Reaper Man, in which we learn that Miss Flitworth has a soul that has remained 18 years old despite her long life.
Mrs. Whitlow is responsible for creating the newzealand: which is like a bikini in that it comes in two halves, but it covers a far larger area, separated by a comparatively narrow strait.
The magical rejuvenation that Mrs Whitlow received in The Last Continent, where exposure to a very strong flux made her look and act so much younger, would have its Roundworld counterpart in hormone rejuvenation therapy (HRT), which has given a new lease of life to many Roundworld ladies of a certain age and which would have been un-thought-of even twenty years ago. Is this, can it be wondered, an intended parallel?
The Colour of Magic briefly mentions a Granny Whitlow, an evil witch who builds a candy cottage and is eventually pushed into an oven by two small children (a la Hansel and Gretel). There may be a relationship between them or Granny Whitlow may be just an alias for Black Aliss?
In Thief of Time, we briefly learn of civic hangman and amateur clock-maker Hepzibah Whitlow, who revolutionized the world of long-case clocks by devising the adjustable pendulum to improve its timekeeping. It is also unknown whether he is related, although from contextual evidence (Jeremy Clockson says long-case clocks large enough to house such a pendulum were devised fifteen years before the present, and this Whitlow is not the current Civic Hangman) he could be a brother or a previous husbands?
A 'whitlow' in Roundworld is a septic abscess on the tip of the finger which is often under the nail, and can be supremely painful.