I HAVE READ ALMOST ALL of them, in all shapes. I've read the bad, fat ones, such as Catherine Breslin's Unholy Child (Dial, $12.95) -- the child is the murdered son of a schizoid Catholic nun -- and The Vicar Of Christ, by Walter F. Murphy (Macmillan, $12.95), a three-layered life history of a Catholic-American pol who becomes pope. I've read the good, fat ones, such as Norman Mailer's The Executioner's Song (Little Brown, $16.95), a mammoth account of the life and death of murderer Gary Gilmore, and William Styron's first novel in many years, Sophie's Choice (Random House, $12.95), which ranks high among the year's most moving and impressive works. I've also read the thin, sensitive Chekhovian novels, which are abundant this year, fortunately, because my tastes run to these.

There is on my list a disproportionate number of short story collections. I like the form, for it permits the kind of experimentation in voice that I find the most interesting part of fiction. So I read every serious volume of stories that comes my way, and some very good collections are available this year.

I enjoyed especially the stories of two young women new to publishing: Black Tickets, by Jane Anne Phillips (Delacorte, $8.95; paperback, $4.95) and Vanishing Animals and Other Stories, by Mary Morris (Godine, $10). Both writers have unique narrative voices and have produced notable first volumes. There are books by old hands at the short form: John Updike's Problems and Other Stories (Knopf, $10), which resemble, in subject and in style, many other stories Updike has written; and Irish writer William Trevor's Lovers of Their Time (Viking, $10.95), a continually absorbing book in which the stories never sound like the ones that preceded them. V. S. Pritchett's extremely good new volume, On the Edge of the Cliff (Random House, $8.95), is about how life is lived in our peculiar times. I very much liked Ward Just's new collection, especially the novella which gives it its title, Honor, Power, Riches, Fame, and the Love of Women (Dutton, $8.95); Edna O'Brien's A Rose in the Heart (Doubleday, $8.95), whose stories about upper-class levels of society are wonderfully crafted and vivid; Oilers and Sweepers, by George Dennison (Random House, $7.95) by a writer we expect to see in other literary areas now venturing successfully into short fiction, and Guy Davenport's "factions," Da Vinci's Bicycle (John Hopkins, $12.95); paperback, $4.95), an interesting experimental volume, and a welcome sign that university presses are investing in fiction. Finally, there is that horrifying and at the same time exciting volume of short stories, In Between the Sheets (Simon & Schuster; $8.95), by Ian McEwan, who last year wrote a parable of evil in the lives of children, The Cement Garden.

In fairness, I must mention four books liked very much by others, but not by me. I found Mavis Gallant's stories in From the Fifteenth District (Random House, $8.95) too stylized and bloodless for my tastes; Secrets And Surprises, by Ann Beattie (Random House, $8.95) still as flat, blank and motionless as her work has always seemed to me; I Know Your Heart, Marco Polo, by Henry Bromell Knopf, $7.95) uninteresting and unimpressive. I am tired, I find, of Donald Barthelme's style, so Great Days (Farrar, Straus and Giroux, $7.95) held me for a third of the book, and then I abandoned it. These voices, and the stories they tell did not command my interest.

The novels I cared about, and which are firmly fastened in my memory as we slide into the new decade, are in two piles. The first contains what you might expect, the books everyone, including the critics, agree are important and valuable. They've each been reviewed almost everywhere. In the second pile are those I liked enormously although others paid scant heed to them or reviewed them negatively.

The first group -- written by established novelists, who have been well-respected ever since their work began to appear in the '40s and the '50s -- is easier to deal with. Philip Roth made a remarkable return to the front rank of American novelists with The Ghost Writer, (Farrar, Straus and Giroux, $8.95), and unforgettable and somewhat autobiolographical story of a young Jewish writer's overnight pilgrimage to the country home of the admired, older Jewish novelist, his wife and a young woman who insires a fantasy about Anne Frank. Bernard Malamud added to his distinguished list of fiction Dubin's Lives (Farrar, Straus and Giroux, $10), about a middle-aged biographer whose existence in Vermont is shaped by his preparation for writing the life of D. H. Lawrence. Harper & Row has published an early, vintage Gabriel Garcia Marquez work, In Evil Hour ($8.95).

Kurt Vonnegut published Jailbird (Delacorte/Seymour Lawrence, $9.95), a novel everyone agrees was one of the best, even after a long line of popular successes. The ubiquitous John Updike weas responsible for not one but two volumes of short stories -- Fawcet issued Too Far to Go (paperback, $2.25), a gathering of 20 Maple stories from that autobiographical couple's marriage to their bittersweet divorce -- following his stunning, and stylistically elegant novel of last year, The Coup (Knopf, $8.95), a perfect marriage of decorative Updike prose and African rhetoric.

After a long absence from fiction, Mary McCarthy appeared in print in an unaccustomed form. Cannibals And Missionaries (Harcourt Brace Jovanovich, $10.95) is a successful and timely adventure-suspense story about the hijacking of a plane full of Americans on their way to Iran. Brian Moore the Irish writer of note, is responsible for The Mangan Inheritance (Farrar, Straus and Giroux, $10.95), another in his line of subtle novels (including The Lonely Passion of Judith Hearne and Catholics). I liked it somewhat less than some of his earlier work but was impressed, as usual, with his technical skill in telling a good story.

Nadine Gordimer's novel, Burger's Daughter (Viking, $10.95), about the lives of wh ite liberals in South Africa, seemed to me to be too heavily ideological, but others, I saw in reviews, felt that politics and persons were quite properly meshed in her text. I was especially taken with William Golding's curious, complex and pessimistic new work, Darkness Visible (Farrar, Straus and Giroux, $10.95). The author of Lord of the Flies has written a fictional challenge that requires close reading, rewarding the student of its murky depths with the pleasures of recognition.

To my way of thinking, the major disappointments of the year, by major writers, were these: Just Above My Head, by James Baldwin (Dial, $12.95), which repeats, in themes and scenes, earlier Baldwin successes; Joseph Heller's Good as Gold (Simon & Schuster, $12.95), which I found repetitious, unfunny and downright dull for long stretches; Muriel Spark's Territorial Rights (Coward, McCann, $9.95), which demonstrated a sad loss of wit by the author of The Prime of Miss Jean Brodie; Joyce Carol Oates' annual (or biannual?) book, Unholy Loves (Vanguard, $10.95) with little but the author's awesome reputation to recommend it; and doris Lessing's interminable Shikasta (Knopf, $10.95), her pedestrian start on a five-novel science-fiction enterprise.

In the same lamentable category: John Barth's Letters (Putnam, $16.95), a hefty, expensive and on the whole, unavailable novel to the newcomer to his fiction. Stanley Elkin, my usual choice for American humorist of our time, fell off somewhat, I thought, with The Living End (Dutton, $7.95) a slight, afterlife satire. Gilbert Sorrentino's Mulligan Stew (Grove paperback, $12.50) is a huge, experimental, often very funny work, but I grew weary of it long before the end, unlike a few people who thought it was the best book of the year.

As for the smaller, less bulky, more delicate and suggestive novels, books of a size to slip unnoticed between the hype for BIG books by BIG writers, there were some excellent ones. My favorites were, in no special order: John Hawkes' The Passion Artist (Harper & Row, $9.95), the book I think stands the best chance of being read again and again, and of being studied critically. Too complex for a sentence of summary, the book is, like Kafka, deceptively simple in its telling, profound in its implications.

Elizabeth Hardwick's lovely, if episodic and unconventionally organized, Sleepless Nights (Random House, $8.95); Alison Lurie's slight but absorbing study of a Fourth of July weekend "away" with young girls and their families, Only Children (Random House, $9.95); Birdy by William Wharton (Knopf, $8.95) -- the most original novel of the year -- about a young boy who is obsessed with birds, a species he prefers to Homo sapiens; Stealing Home by Philip O'Connor (Knopf, $8.95), a loving, faithful and entirely persuasive story of a man who manages his son's Babe Ruth League baseball team; and a lovely sleeper, Vision Quest (Viking, $8.95), a bildungsroman by Terry Davis that is almost as good as the one Stalinger wrote. It concerns a high-school senior who is preparing for his last wrestling match before graduation. Three others I liked: Bernard Packer's The Second Death of Samuel Auer (Harcourt Brace Jovanovich, $10.95), a fine, evocative novel about Jewish-black life in South Philadelphia; Clark Blaise's Lunar Attractions (Doubleday, $8.95), an unsentimental and beautifully written novel about a boy growing up in Florida, and much more; and a book I much admired, When the Tree Sings, by Stratis Haviaris (Simon & Schuster, $9.95), the almost poetic novel by a poet about his boyhood experience in waretime Greece.

Mea culpa department: I never got around to reading Endless Love, by Scott Spencer (Knopf, $10.95), which a friend told me not to miss. I tried to get through Harold Bloom's murky The Flight to Lucifer: A Gnostic Fantasy ( farrar, Straus and Giroux, $9.95) without success. I found Eleanor, by Rhoda Lerman (Holt, Rinehart,$10) unconvincing and thin. I got halfway through McKay's Bees, by Thomas McMahon (Harper & Row, $8.95) and gave up. For no good reason, I neglected to read Jerry Kosinski's Passion Play Martin's, $11.95), and Living in the Maniototo, by Janet Frame (Braziller, $8.95), whom I've always admired. They will go with me on the perilous descent into the '80s.