The Witch is a fascinating Archetype- immediately distinctive and recognizable, capable of expanding into a collective while preserving the capacity for individualism. Nuns kind of work the same way (as shows such as Nunsense and Sister Act have discovered): there’s an “alikeness” to Nuns, balanced by an individuality to each specific Nun, that gives Nuns the same comic potential found in Witches. The Shrek movies have long since discovered the comic value of inserting a random Witch into crowd scenes: for some reason, Witches can be funny all by themselves (the sight gag of a figure with a pointed hat on her head), and few other Archetypes are established as quickly or as cleanly, as the pointed hat establishes the Witch. In the fourth Shrek installment, Shrek: the Final Chapter (also known as Shrek: Forever After), the stray sight gag of a Witch (intended to add verisimilitude to the Fractured Faerey-Tale environment of Shrek’s world) is multiplied into platoons of supporting characters, adding a Witch-infused anarchy to the scenes.
In the aftermath of a Magickal trick, the pint-sized tyrant Rumpelstiltskin gains despotic control over Far, Far Away- an authority enforced by a veritable Luftwaft of night-flying Witch-Stormtroopers. Meanwhile, he turns the palace into his own Club Empire, attended by a bevy of sycophantic Party-Witches; whom he holds cowed and terrorized in the film’s best scene, threatening each with a glass of water (which of course, eventually gets splashed into the face of one unlucky Witch, who melts away murmuring with sadness, “What a world! What a world!”) The humor of the scene builds upon an established cultural Witch-past, and the acceptance of certain Pop-Culture Witch tropes, as does the movie as a whole.
One of the curious things about comedy, is understanding how it works: what makes something funny, while something else is not. An inexact science, but a deeply intriguing one; as Shrek Forever After demonstrates, some things just become more interesting and amusing, when done by a Witch.
When she succeeds in acquiring one silver shoe by making Dorothy trip over an invisible bar, the little girl angrily throws a bucket of water onto the Wicked Witch. This, of course, causes the old witch to melt away. L. Frank Baum didn’t explain precisely why water had this effect on her, nor did he ever imply that all witches could be likewise put out. He does, however, mention that the witch was “so old” and so wicked, that all the blood in her body had dried up many years ago. Thus, it might be surmised that water was fatal to her on account of her extreme and unusual dryness.