Adorno is the big one - his cynicism toward absolutely everything offers a really bracing example of the possibilities and pitfalls of critical analysis toward one’s own culture. Also Kafka, Sontag, Gilbert Sorrentino, Gertrude Stein to a degree.
Ray Bradbury- the wild heart-warming & heart-breaking possibilities of the imagination in a universe of small-town kids, dark carnivals, Martian ghosts & electical grandmoms.
Andrew Greeley- emotionally-wounded and confused people can be thrown together by a Wild Love-Crazed God.
Ayn Rand- The self can not and should not be destroyed. A healthy respect for oneself AND other selves keeps the engine of society running.
Brad Steiger- there are tons of things, ancient & modern, physical & psychological, that defy explanation and point to other realities than our everyday one
C.S. Lewis- Christian faith, deep thought & wild imagination all swirled together perfectly
Bram Stoker- monstrous evil lurks to destroy purity & innocence & it takes faith & bravery to stand against it.
Mary Shelley- You are responsible for what you create, and to be as kind & fair as possible to those you encounter.
Hal Lindsay- God speaks through the Bible to individual lives, ethnicities & civilizations to work out the Reign of Jesus (I no longer believe exactly in Lindsay’s view of how God works this out but he first got me thinking in these lines.)
Taylor Caldwell- Faith-filled individuals must wrestle with Divine Silence, devilish plots & the tragic beauty of everyday life, even if that wrestling overwhelms them.
Walker Percy- There is Meaning, hidden & elusive, but present & ultimately leading to Christ, who occasionally but seldom manifests Charismatic wonders & Apocalyptic signs, but more often in the love of others, who are Gifts and therefore Signs of The Giver.
I think that sums it up! Though I’m sure I could come up with more if need be.
Douglas Adams. Mark Twain. R.A.H. Asimov. (not so much Clarke)
William Golding. (Lord of the Flies. Read it at 4 or 5. Bad idea.)
Douglas Hofstadter. (Godel Escher Bach)
Fiction: 1984 - George Orwell. This one really influended by political beliefs about the limits of government power, and I still can’t look at a security camera in a public place without thinking about it.
Non-fiction: The Language Instinct - Steven Pinker. Pop science classic which totally convinced me, though I’m still not completely sure if this is because he’s such a readable writer or whether is it because he’s actually right. I very nearly studied Linguistics because of it and did go on to study Philosophy of Language.
And Diana Wynne Jones and Tonke Dragt (an excellent Dutch childrens’ author) got me hooked on fantasy as well as setting the standard sufficiently high for me to be disappointed with a lot of subsequents reads in that genre.
As the person that first said how much Heinlein had influenced their views on the other threadI have to stick with this. Pro-science, pro-self reliance, pro-achieving one’s full potential, pro-sceptical thinking, anti-Mrs Grundy intrusions into private lives. One more surprising aspect I picked up was a feeling that “magic” ought to work. Telepathy, telekenisis, straight out magic all feature in what is supposedly hard science fiction:dubious:
Other influences: umm… well I have to thank John D MacDonald for my understanding of US life in the sixties and seventies and Ian Flemming for a grounding in the history of the Cold War 
George Orwell—Basically, he taught me to be suspicious of anyone who wants power. Like C.S. Lewis, he was an excellent essayist whose common sense and common decency were most uncommon. His insights into how politics corrupts language have been particularly useful. I’ve read everything by him I could find.
Ayn Rand—Okay, her philosophy as a whole doesn’t work, and that’s putting it mildly. But she taught me a healthy contempt for the average so-called intellectual, she drummed it into my head that a need is not a right, and like Orwell she had an almost eery grasp of how statism invariably leads first to corruption and then to tyranny.
Colin Wilson—the early Wilson, not the later Wilson who became just another New Age moonshine peddler. In my younger days, I was a hard core atheist and materialist. The Outsider, Religion and the Rebel, and *Poetry and Mysticism *put some very big cracks in that wall.
Russel Kirk—I read Kirk’s *The Conservative Mind *at the same time that I read Michael Harrington’s Socialism. Kirk won, and it wasn’t even close.
G.K. Chesterton , C.S. Lewis—Like Wilson, Chesterton and Lewis put serious cracks in my materialism and got me to question modernism and “progress” for the first time.
Jared Taylor—*Paved with Good Intentions *finally got me to give up altogether on egalitarianism, multiculturalism and the worship of diversity.
Robert Ardrey—I read *African Genesis *at an early age, and it impressed upon me the fact that human beings are no less subject to instincts such as territoriality, status seeking and tribalism than other mammalian species.
Eric Hoffer—*The True Believer *gave me still more reasons to be suspicious and skeptical of idealism and mass movements.
Karl Marx—Like Rand, he was mostly wrong, but his concept of class conflict does much to explain the history of the past few centuries.
Taylor Caldwell influenced me quite a bit in my adolescence, although as I’ve become agnostic- I’ve outgrown quite a bit of it.
C.S Lewis- Although I’ve only read the Chronicles, almost all of them have ideas and scenes that I return to often. Specifically, the idea of the Tash follower/soldier that was granted entry into the next world because although he was a seeker of the truth/served Tash in the name of good.
Irvine Welsh- who unlocked the more $%%@ part of me and made me realize the importance of good dialogue.
Larry McMurtry- for the realism, characters and dialogue. The writer I hope to be when I grow up.
I have less than four minutes before I have to leave so I will leave out a bunch.
Mark Twain
Kurt Vonnegut
Issac Asimov
F. Scott Fitzgerald
Ayn Rand
Dumas
Ray Bradbury
Arthur Conan Doyle
Aldos Huxley
Sabatini
Have to go!
I’m going to add Stephen King to my list; not necessarily for the same reason as other authors, but more for the way I have to think critically of his novels to defend them against intellectuals who are all too willing to dismiss them simply for their popularity. His writing has made me understand that you can be the master of parts of a field without being a classical Capital A Author.
I haven’t seen anyone “dismiss” them simply for that.
I’m sure there are more, but the first writer who comes to mind is Vonnegut. I’d read most of his books by the time I was fifteen, and I think they had a pretty profound influence on the way I think, especially with how to deal with bad things that are outside of my control.
Friedrich Nietzsche – probably the number one influence on my understanding of the world, particularly as it relates to the question of suffering. I could write a novel about Nietzsche’s influence on my life.
Robert Musil – A close second. ‘‘The Confusions of Young Torless’’ is hands-down one of the most influential books I’ve ever read. It’s basically about nihilsm and torture at a boys’ military school, and is probably based on actual events. What it’s really about, though, is just this kid trying to find a moral anchor in a sadistic and brutal world. I would never do what he did, but I get that struggle. Musil and his counterparts, Sartre, Kafka, Conrad, Camus, etc. they all powerfully expressed the absurd, cruel, and arbitrary nature of reality that I always felt but could never fully articulate.
Viktor Frankl – Nietzsche’s kinder, gentler successor, who taught me to start at Will to Power and end with something that benefits all of mankind. This man practiced delivering lectures on surviving trauma before imaginary audiences while he was imprisoned during the Holocaust. He gave existential therapy to other Holocaust survivors while he was experiencing it himself. Do I even have to explain how fucking amazing that is?
Albert Ellis – The loud-mouthed, pushy co-founder of cognitive psychology who totally challenged the millions of negative irrational thoughts I used to have day in and day out. Ellis is all about common sense and won’t hesitate to call anyone on their self-deprecating bullshit. I highly recommend his stuff for anyone looking for an evidence-based treatment for depression or anxiety who isn’t afraid of a little ass-kicking.
An eclectic bunch in no particular order:
Rabelais
Carl Barks
Valmiki
Virginia Woolf
Kalidasa
Chris Ware
Søren Kierkegaard
Abhinavagupta
James Joyce
Max Stirner
Melville
Hermann Hesse
Nietzsche
Homer
Goethe
Thoreau
whoever wrote the Mahabharata
Thomas Mann
Per Højholt
Eta: Olives, I have a feeling that you would like Stirner. The Ego and it’s Own Der Einzige und sein Eigentum predates Nietzsche and is a work preaching anarchistic individualism while pinpointing the follies of any kind of idealism. Highly entertaining and quite poignant.
Robert Anton Wilson
Oh. I forgot Roald Dahl and George Orwell. (Animal Farm has talking animals. It’s a kid’s book! See: Lord of the Flies.)
Charles Schultz.
Dr. Seuss.
C.S. Lewis.
That’s pretty much the stuff from the ages of 8 and before that really stuck with me even today.
Frank Herbert. Dosadi Experiment in particular. his ideas on training and longer than a single human lifetime research projects were very very interesting.
quite a few already listed otherwise.
Seconded. I’m re-reading Minima Moralia for the first time in 20 years, and it still makes an impact.
I’d also add Samuel Beckett, Greil Marcus, Steven Pinker, Kurt Vonnegut (though I haven’t read him since I was a teenager), Camus, Wittgenstein, and, of course, Mark Twain.
Non-“literature”-wise, I’d have to be honest and say both Mad and Creem magazines influenced me greatly. Both did a pretty great job of calling out the absurd and downright stupid aspects of modern culture in a humorous way; maybe it would be going a bit far to call them “Swiftian”, but, at different ages, they served the same function for me.
I hadn’t been thinking back that far, but now that you mention it, excellent call. Another vote for Vonnegut, and I’ll add Tom Robbins.
Of course Rand (and Branden).
Also Aristotle, Nietzsche, Heinlein, Bradbury, James Baldwin, Hannah Arendt, Walter Kaufmann . . . and Ann Frank.
Possibly Terry Pratchett.