If horror resides in the tone of a work rather than specific content, there is a case for virtually all of Joyce Carol Oates's work to be so classified. Certainly there is a thick vein of darkness throughout. Her work displays a highly literary sensibility (derived in part from the "Southern Gothic" of such as William Faulkner and Flannery O'Connor and in part from contemporary mainstream - she is particularly fond of using the present tense, for example) and at the same time is always intense, often violent, turbulent and sometimes - deceptively - seeming barely in the author's control. (Bellefleur, at nearly 300,000 words probably her longest novel, is a particular case in point. Compare its opening sentence with that of Isabel Allende's The House of the Spirits: both are a page long, but Oates's prose has the qualities described above - by contrast Allende's seems the epitome of authorial control.) Redemptive endings, like that of What I Lived For, are rare and hard-won, our reward for following the collapse of the life of the protagonist, successful businessman Jerome "Corky" Corcoran, over one long Memorial Day weekend and 600 pages. (It should be noted in passing that Oates is extremely good at writing about men - Corky is thoroughly convincing. The story "Golden Gloves", collected in Raven's Wing, about an ex-boxer's experience of impending fatherhood, is another fine example, particularly when one considers that Oates herself is childless.)

Oates is a remarkably prolific writer. Certainly there are less successful works in her bibliography: Expensive People, about a son's plot to assassinate his mother, is a heavy-handed attempt at black comedy (humour is definitely not Oates's forte); Childwold contains powerful passages but is incoherent. Some novels are routine by her standards, strong writing that somehow falls flat, fails to connect: Angel of Light and Cybele particularly come to mind. Many of her early novels and stories feature seemingly arbitrary violent conclusions which do not arise naturally from the preceding events.

Her range of character and subject matter is wide: from the campus novel (Unholy Loves, American Appetites, the latter also a courtroom drama) to Victorian genre pastiche (Bellefleur, A Bloodsmoor Romance, Mysteries of Winterthurn), from stories of transgressive desire (interracial in Because it is Bitter, and Because it is My Heart and I Lock My Door Upon Myself, incestuous in You Must Remember This and the title novella of A Sentimental Education) to semi-autobiography (Marya: A Life, one of her best). Those published under the pseudonym Rosamond Smith (a name derived from that of her husband, Raymond Smith), are psychological suspense thrillers.

If one defines horror as a genre using certain themes and tropes, Oates is undoubtedly a writer who uses some of them in her work. Though published as a mainstream writer, she is certainly no stranger to horror, with publications in genre magazines such as Omni and Twilight Zone and anthologies including Metahorror (edited by Dennis Etchison, 1992) and Skin of the Soul (edited by Lisa Tuttle, 1990). Supernatural events are rare, though Night-Side and Haunted collect some exceptions to this rule. Son of the Morning, a fever-dream of a novel and one of her best, features an evangelical preacher who is granted seven visions, each more terrifying than the last, notably a memorable scene where, on live TV, he takes literally the edict "If thine eye offends thee, pluck it out". The horror in Oates's work derives more from people's behaviour and states of mind. Bizarre events do occur, but they are of a kind that may be unusual but is not impossible.

Bellefleur, a seven-generation anti-chronological family saga, is a case in point. Germaine, the central character, absorbs a male twin in the womb; all that remains of him are his genitals, growing from her chest. Even in Foxfire, a 50s-set account of life in a girl gang (filmed in 1996), there is a disturbing, almost extraneous episode where two of the gang members witness the sexual exploitation of a retarded dwarf woman. Wonderland depicts a cycle of horror in one life: Jesse, the protagonist, is the only one to escape the massacre of his family by his father, who then kills himself. Taken in as an orphan by a doctor, Jesse becomes a distinguished brain surgeon himself (via some harrowingly-described hospital scenes). He marries unsuccessfully and has an affair, and alienates his daughter. The near-victim of infanticide by his father has become a dysfunctional father himself. "Martyrdom" (collected in Haunted - originally published in Metahorror) juxtaposes an abused woman and a laboratory rat, who meet in an ending probably inspired by Bret Easton Ellis's American Psycho. "In the Warehouse" (The Goddess and Other Women) begins as a memoir of teenage-girlhood friendship and ends as something else: the narrator murders her stifling "friend" with impunity. In the book-length novella Black Water, a woman drives into a river during a storm. We flash back over her recent life and how she came to be driving at this time and to this place, while she drowns.

Zombie, for which Oates won the Stoker Award (her second, after one in 1994 for continuing achievement), is something of a departure. Told in a first-person narrative (unusual for Oates) in which some literary flourishes sit occasionally awkwardly, it is the story of Quentin P_, a sexual psychopath (preying on young men) whose life's project is to make the zombie of the title. He disassociates himself from his victims by giving them nicknames (Bunnygloves, Raisineyes, Squirrel) and sometimes referring to himself in third person. The text is interspersed with some of Quentin's crude drawings. His attempts are foiled by ineptitude, but Quentin is almost comical in his persistence; the novel's achievement is that we recognise the human in him, although what he does is aberrant. At the end of this short novel, he has his eyes on another potential zombie - life goes on.

Oates at her finest is a living refutation of the belief that a prolific output and high literary quality are incompatible. Her bibliography is prodigious, her quality-rate high, both still continuing.