Real SKs represent a late-20th-century nadir of human stupidity, and thus are the antithesis of fantasy. Fictional SKs who are carriers of the toxins of Horror have some small place here. Also, whether we like it or not, the image of the SK has gained iconographic status well outside horror, as in the Psychological Thriller.
Dracula is a serial killer, and most books or movies about Vampires are about serial killing. The paradigm SK is of course Jack the Ripper, who is rarely a figure of fantasy interest, though some version of the man can be found in Gaslight Romances like Kim Newman's Anno Dracula (1992). Jack is a paradigm figure because unseen, indulgent in splatterpunk excesses of sadism, uncaught, has a rough Trickster wit (as has Hannibal Lecter in The Silence of the Lambs  by Thomas Harris [1940- ]) and is chased fruitlessly by the law. Barbara Hambly's Those Who Hunt the Night (1988) is dependent on these characteristics. Other SK novels with some fantasy interest include James Herbert's Moon (1985), Dean R Koontz's The Bad Place (1990), Simon R Green's Shadows Fall (1994) and Poppy Z Brite's Exquisite Corpse (1996). The Hellblazer comic (1988- ) by Jamie Delano and others, with John Constantine as created by Alan Moore, features encounters with SKs.
Movies which make play with SKs are frequent. Those of fantasy interest include the Kolchak Movies, Don't Look Now (1973), Eyes of Laura Mars (1978); Cat People (1982), the Nightmare on Elm Street series, Lady in White (1988), Barton Fink (1990), Nightbreed (1990) and Candyman (1992). [JC]