Several of the films in the informal canon I've constructed were based on novels, as indeed such a large number of films tend to be. Do these books get elevated to a particular kind of quasi-canonical status? Presumably, a bad film adaptation won't make a book less esteemed (though you do have to wonder about The Bonfire of the Vanities...) if only because we can all state with certainly that any untalented schmuck could exploit a great novel to make a crappy film. The opposite scenario, though, is certainly intriguing. Does Kubrick's The Shining, which seems to become more canonical by the day, make Stephen King's The Shining more significant? Not better, of course, but more canonical: that is, do we recommend it as the first King novel to read (if any) or rank it as an important genre-fiction work? There's also the possibility that the two works in question could mutually benefit from a film adaptation. That is, the film causes readers to reconsider the book; this elevation of the book's status in turn makes the film seem more significant.
A list of literary works on which some of our canonical films have been based (if the titles aren't the same, the film is listed first---Wikipedia links provided):
Rules of the Game:
Alfred de Musset - Les Caprices de Marianne 
The Wizard of Oz:
L Frank Baum - The Wonderful Wizard of Oz 
Ryunosuke Akutagawa - 'Rashoman'  and 'In a Grove' : stories used as the basis for the film Rashoman
Sunrise: A Song of Two Humans:
Hermann Sudermann - 'Die Reise Nach Tilsit' (Trip to Tilset), part of Lithuanian Stories 
Bibhutibhushan Bandopadhyay - Pather Panchali 
Margaret Mitchell - Gone With the Wind 
It's a Wonderful Life:
Philip Van Doren Stern - The Greatest Gift 
Privately published as a monograph at first, this story was featured in Reader's Scope and Good Housekeeping magazines (in the latter as 'The Man Who Was Never Born').
Pierre Boileau and Pierre Ayraud, under the pseudonym Thomas Narcejac - D'Entre les Morts (The Living and the Dead) 
Alan Le May - The Searchers 
Robert Bloch - Psycho 
Peter George [under the pseudonym, Peter Bryant] - Two Hours to Doom; later re-titled Red Alert 
Charles Webb - The Graduate 
Arthur C Clarke - 2001: A Space Odyssey  Developed in tandem with the film
Mario Puzo - The Godfather 
Jake LaMotta - Raging Bull: My Story 
Thomas Keneally - Schindler's Ark; titled Schindler's List for U S version 
Nicholas Pileggi - Wiseguy: Life in a Mafia Family 
Murray Bennett and Joan Alison's Everbody Comes to Rick's was meant to be a play, but had not been performed when it was sold to Warner Brothers and was adapted to film as Casablanca.
Graham Greene wrote the screenplay for The Third Man, but had also written a novella version to prepare for writing the script; the novella was published after the film.
On the Waterfront is based on a series of New York Sun articles by Malcolm Johnson entitled 'Crime on the Waterfront'; these have been published in book form.
More novels that have been made into films that were critically acclaimed or at least are of significance to cinematic history, and well-regarded novels whose cinematic adaptations have not necessarily been successful:
Warren Adler - The War of the Roses
John Ball - In the Heat of the Night
Larry Beinhart - American Hero [Wag the Dog]
Peter Benchley - Jaws
John Boland - The League of Gentlemen
Pierre Boulle - La Planète des Singes (The Planet of the Apes); Le Pont de la Rivière Kwa (The Bridge on the River Kwai)
Lothar-Günther Buchheim - Das Boot
James M Cain - Double Indemnity
Truman Capote - Breakfast at Tiffany's
Camilo Jose Cela - La Colmena (The Hive)
Pat Conroy - The Great Santini; The Prince of Tides
Philip K Dick - Do Androids Dream of Electric Sheep? [Blade Runner]
Alan Duff - Once Were Warriors
Umberto Eco - Il Nome Della Rosa (The Name of the Rose)
Ivan Efremov - Tumannost' Andromedy (The Andromeda Nebula)
Mircea Eliade - Tinereţe Fără Tinereţe (Youth Without Youth)
Hans Fallada - Kleiner Mann, Was Nun? (Little Man, What Now?)
Helen Fielding - Bridget Jones's Diary
Jack Finney - The Body Snatchers [Invasion of the Body Snatchers]
Vardis Fisher - Mountain Man [Jeremiah Johnson]
Fannie Flagg - Fried Green Tomatoes at the Whistle Stop Cafe
James Fogle - Drugstore Cowboy
Neil Gaiman - Stardust
Benito Perez Galdos - Tristana
Brian Garfield - Death Wish
Telman Gdlyan and Evgeny Dodolev - Piramida (The Pyramid: The Soviet Mafia)
Graham Greene - Brighton Rock
Harry Grey - The Hoods [Once Upon a Time in America]
Robert Groom - Forrest Gump
Davis Grubb - The Night of the Hunter
Judith Guest - Ordinary People
Arthur Hailey - Airport
Craig Harrison - The Quiet Earth
Patricia Highsmith - The Talented Mr. Ripley
Oscar Hijuelos - The Mambo Kings Play Songs of Love
S E Hinton - The Outsiders; Rumble Fish
Hirotsu Kazuo - Chichi to Musume (Father and Daughter) [Late Spring]
P D James - Children of Men
Nikos Kazantzakis - Zorba the Greek
Ken Kesey - One Flew Over the Cuckoo's Nest
W P Kinsella - Shoeless Joe [Field of Dreams]
C J Koch - The Year of Living Dangerously
Mykhailo Kotsiubynsky - Teni Zabytyh Predkov (Shadows of Forgotten Ancestors)
Milan Kundera - Nesnesitelna Lehkost Byti (The Unbearable Lightness of Being)
Giuseppe Tomasi di Lampedusa - Il Gattopardo (The Leopard)
Stanislaw Lem - Solaris
Norman Maclean - A River Runs Through It
Norman Mailer - The Executioner's Song
Bernard Malamud - The Natural
Whit Masterson - Badge of Evil [Touch of Evil]
Richard Matheson - I Am Legend [Omega Man]
W Somerset Maugham - The Razor's Edge
Cormac McCarthy - No Country for Old Men
Ian McEwan - Atonement
Rick Moody - The Ice Storm
Alberto Moravia - Il Confirmista (The Conformist)
David Morrell - First Blood
Robert C O'Brien - Mrs. Frisby and the Rats of NIMH [The Secret of NIMH]
Rex Pickett - Sideways
Charles Portis - True Grit
Barry Reed - The Verdict
Suzuki Koji - Ringu (Ring)
Leonardo Sciascia - Il Giorno Della Civetta (The Day of the Owl); A Ciascuno il Suo (To Each His Own)
Hubert Selby, Jr. - Last Exit to Brooklyn
Dr. Seuss - The Lorax
Wladyslaw Spzilman and Jerzy Waldorff - Śmierć Miasta (Death of a City)
William Styron - Sophie's Choice
Amy Tan - The Joy Luck Club
Roderick Thorp - Nothing Lasts Forever [Die Hard]
F X Toole - Rope Burns: Stories From the Corner [Million Dollar Baby]
Armitage Trail - Scarface
B Traven - Der Schatz der Sierra Madre (The Treasure of the Sierra Madre)
Anne Tyler - The Accidental Tourist
Gore Vidal - Myra Breckinridge
Irvine Welsh - Trainspotting
Nathanael West - The Day of the Locust
E B White - Charlotte's Web
Gary K Wolf - Who Censored Roger Rabbit? [Who Framed Roger Rabbit?]
Marguerite Yourcenar - L'Oeuvre au Noir (The Abyss)
Stefan Zweig - Ungeduld des Herzens (Beware of Pity)
Several of August Le Breton's and Joseph Kessel's novels have become films, though Elmore Leonard and Stephen King are the true titans in this category.
Jerzy Kosinski's Being There , basis for the Hal Ashby film of the same name, caused much controversy, as it's apparently based (excessively... as in plagiarism) on the Polish novel, The Career of Nikodem Dyzma, by Tadeusz Dołęga-Mostowicz
While Stanley Kubrick is probably the greatest filmmaker who made literary adaptations almost exclusively, another brilliant cinematic interpreter of literature is the Japanese director Kon Ichikawa, who adapted among other novels Mishima's The Temple of the Golden Pavilion (as Enjo, 1958) and Natsume Soseki's I Am a Cat.
Of television series adapting literary works, Rainer Werner Fassbinder's Berlin Alexanderplatz is commonly seen as a masterpiece. A recent project of note is the Brazilian television network Rede Globo's soap opera version of José Marqia de Eça de Queirós's Os Maias.
Back to the cinema, a series of books by Warren Murphy and Richard Sapir, The Destroyer, birthed only a single film, Remo Williams: The Adventure Begins. Further installments never came to be.
Similar to On the Waterfront, Urban Cowboy was based on a magazine article, in this case of the same name, written by one of the two screenwriters, Aaron Latham, published in Esquire; James Bridges worked with Latham on the adaptation.
Similar to Wiseguy, other non-fictionworks have become "based on real events" films: Born Free; Le Scaphandre et le Papilion (The Diving Bell and the Butterly); A Beautiful Mind; Lost Moon: The Perilous Voyage of Apollo 13 [Apollo 13]; Girl, Interrupted; Empire of the Sun; Moneyball: The Art of Winning an Unfair Game; Dead Man Walking; The Basketball Diaries; The Untouchables; All the President's Men; I Am a Fugitive From a Georgia Chain Gang! [I Am a Fugitive From a Chain Gang]; Into the Wild; Confessions of a Dangerous Mind; The Longest Day; The Orchid Thief [Adaptation]; Jarhead; Flags of Our Fathers; Picture Letters From Commander in Chief [Letters From Iwo Jima]; Friday Night Lights: A Town, a Team, and a Dream; Out of Africa.
Russian Ark is based in part on La Russie en 1839 by the Marquis de Custine.
Short stories become movies:
George Langelaan's story 'The Fly', first published in Playboy, Jun. 1957, has spawned several films, while H P Lovecraft's 'Herbert West: Reanimator' inspired the Re-Animator movie series.
Annie Proulx's 'Brokeback Mountain' was originally published in the New Yorker, 1997 and then expanded for its inclusion in Close Range: Wyoming Stories.
Jonathan Nolan's 'Memento Mori', published in Esquire, began to be adapted by his brother Christopher while Jonathan was still working on the story.
Deathdream was inspired by the W W Jacobs story 'The Monkey's Paw'.
'Don't Look Now', a story by Daphne Du Maurier, originally appeared in the collection Not After Midnight.
Of course, playwrights, naturally enough, write screenplays, or adapt their own works for the cinema: e.g., David Rabe's Streamers, John Guare's Six Degrees of Separation, and Tony Kusher's Angels in America, Kaj Munk's Ordet.
The playwright and screenwriter Chayefsky wrote the screenplay for his only novel, Altered States.
Michael Tolkin has worked more as a screenwriter than a novelist; he adapted his novel, The Player, for the Robert Altman film.
An example of a novelist who switched to writing films is William Goldman; several of the films he scripted are noteworthy, but for this discussion his novels, Marathon Man and The Princess Bride, are most relevant: he adapted both for the cinema.
Carl Sagan's Contact began as a screenplay, became a novel when a film couldn't be made; and was finally adapted for the cinema nearly two decades later.
Michael Blake's novel Dances With Wolves was written with its adaptation in mind and indeed he went on to write the screenplay.
Henri La Barthe worked on the screenplay version of his novel, Pépé le Moko.
Flavorwire's 10 Great Movies Based on Poems, though it's one of those dumb list-articles (the popularity of which Buzz Feed seems to be most blame-worthy) from one of those awful advertisement-laden sites that are the equivalent of the free magazines on airplanes, is certainly interesting.