The Dungeon Master's Guide Appendix N is well know to many gamers of a certain age. Maybe too well known really.
In case you are curious, never seen it before, or don't have your DMG handy, here is the list:
Anderson, Poul. Three Hearts and Three Lions; The High Crusade; The Broken Sword
Bellairs, John. The Face in the Frost
Burroughs, Edgar Rice, Pellucidar series; Mars series; Venus series
Carter, Lin. "World's End" series
de Camp, L. Sprague. Lest Darkness Fall; Fallible Fiend; et al.
de Camp & Pratt. "Harold Shea" series; Carnelian Cube
Farmer, P. J. "The World of the Tiers" series; et al.
Fox, Gardner. "Kothar" series; "Kyrik" series; et al.
Howard, R. E. "Conan" series
Lanier, Sterling. Hiero’s Journey
Leiber, Fritz. "Fafhrd & Gray Mouser" series; et al.
Lovecraft, H. P.
Merritt, A. Creep, Shadow, Creep; Moon Pool; Dwellers in the Mirage; et al.
Moorcock, Michael. Stormbringer; Stealer of Souls; "Hawkmoon" series (esp. the first three books)
Offutt, Andrew J., editor. Swords Against Darkness III.
Pratt, Fletcher. Blue Star; et al.
St. Clair, Margaret. The Shadow People; Sign of the Labrys
Tolkien, J. R. R. The Hobbit; "Ring Trilogy"
Vance, Jack. The Eyes of the Overworld; The Dying Earth; et al.
Wellman, Manly Wade.
Zelazny, Roger. Jack of Shadows; "Amber" series; et al.
Certainly a worthy list to be honest.
But it isn't my list.
Yes I read Tolkien during my formative years, followed quickly by Moorcock and Lovecraft. I dabbled in Norton. But I didn't read any Conan till almost a year ago. I had read "A Princess of Mars" before I played D&D, but nothing more till recently and none of the Pellucidar series till almost two years ago.
I have joked, half seriously, that my Appendix N is mostly Hammer Films, 70's exploitation horror, Led Zeppelin, Twilight Zone and Dark Shadows.
But semi -serious for a moment Appendix N was never supposed to be passed on as Holy Writ and there are some notable omissions. Here are some things I would add.
Le Fanu, Joseph Sheridan: CARMILLA. Natch.
Lucas, George: STAR WARS. Star Wars, the first movie, is a D&D adventure writ large. Star Wars and D&D are so forever linked together in my mind it would be hard to tease them apart in terms of which one colors my perception of the other more. This one though is a total cheat as a movie and as one of the "newest" item on my list.
Poe, Edgar Allen. Lots.
Robbins, Russell Hope. Encyclopedia of Witchcraft and Demonology: This book has been long out of print, and I got mine at a used book store, but it is the indespensible work on witches, the witch craze and demonology. The book takes a very pro-witch point of view as it frankly discusses the murder of women, children and even men in the name of god. Not to be missed, this book has been THE source for most of my writings. Several editions are out there, mine is the 1959 edition. I have seen them on Ebay as well.
Smith, Clark Ashton: Everything. No seriously. I discovered CAS after reading about his friendship to Lovecraft. I found a copy of his unfinshed works in the basement of my university library (no joke). I was RIVETED. He spoke to me in ways Lovecraft never dreamed. In particular I recommend his Averoigne series and his Zothique series.
Stoker, Bram: DRACULA; Need to know what else a cleric can do in your group? Let me introduce Prof. Van Helsing. I suggest getting the Annotated Dracula by Leonard Wolf.
There are many others. But these are the ones I keep coming back to.