Two contemporary authors who come immediately to mind are Raymond Carver and Sherman Alexie, both of whom write about the realities of "blue collar" life and the everyday struggles their characters face.
Stylistically, I'd admire both of these writers as well for the subtle craft they exhibit in providing profound insight.
I, too, am now fascinated with an author's style and everything that implies. Long ago, though, I was intrigued by well told stories with intriguing characters. I knew in ninth grade that I wanted to be an English teacher--somewhere along Odysseus's journey home from the Trojan war, I think. I can't just list one influential author; however, there are a few classic stories I re-read every year just because I love the stories and the characters. The Island of the Blue Dolphins and Shane are two of them. Upon reflection, it's the story, yes, but it's mostly the characters. I love the story when I feel connected to the characters, especially those who are conflicted or who have fallen (such as Sydney Carton in A Tale of Two Cities, Cyrano in Cyrano de Bergerac, and John Proctor in The Crucible).
As silly as it seems, The Nancy Drew mystery series inspired my love of reading. In my 3rd or 4th grade way I started to appreciate the writers craft. I noticed such literary things as structure, use of foreshadowing, narrative pace, symbolism, and characterization. I remember distinctly thinking that the author must have a plan for each novel before she wrote and that the elements of the story must all work together to create the overall product in the end.
When I think about authors that influence me, it is usually not their subject matter, but their style that continually shapes my appreciation of other literature. For example, Jay Gatsby doesn't influence my life, but Fitzgarld's meticulous crafting of the novel sets an intellectual standard by which I evaluate other literature for its use of symbolism, color imagery, and setting.
Two authors that I would say had a major impact on my life (especially when I first read them in college) were Anne Lamott and David Sedaris.
Both of these authors seemed to write with such an authenticity in their voices that I could not help but love them, even if I didn't always agree with them. The fact that they've both had some pretty difficult circumstances to overcome in life (mostly due to their own choices) but managed to write about them later with an air of humor has been inspiring to me.
I'm taking what some may consider the shallow road as well and identifying Stephen King. When I picked up my first King book, I was 10 years old. The book was It, and I read all 1,100 pages of it, fascinated at every turn. I can honestly say that this tome paved the way for my career and my passion for literature of all types. And, as an author, Stephen King is a master of the craft...I think though that many are turned off by his subject matter. Not everything he writes is a mind-blowing descent into the human psyche, but I've never been touched by anyone's books the way I have by King's novels. I always end them feeling more a part of the world, and of the human race, if that makes any sense. Also, reading Stephen King has led directly to reading some of my other favorite authors, usually through a mention or review by King. Through his recommendations, I've found Neil Gaiman, Peter Straub, Bentley Little, Harlan Ellison, and Joe Hill.
Second is Kurt Vonnegut, all the way. He tells the truth at all costs, even when that truth is fiction. His books are honest in a way that few authors match, and he seems to genuinely care about both his work and his readers. Certinaly reading him makes me care, about my life and those around me. I wish I had the chance to hear him speak before he died.
The older I get, the more I realize how insightful Shakespeare was about human nature and people in general. Modern situations seem to parallel situations in Hamlet, Othello, King Lear, Macbeth. In Lear, we see how easy it is for the older more powerful ones to be misled and manipulated by the younger ones. In Hamlet, we see the extent of political corruption and a dysfunctional family. In Othello, we see how jealously can wreak havoc on a relationship. When I look at the world, it is with Shakespeare's lenses. So, I guess, William Shakespeare is the author who has played the most major role in my life.
For me, Henry James has to be a major author whose work has shaped me and whose literature I love. What he manages to bring to literature is an amazing psychology of character that penetrates to the heart of motivation and thinking. My favourite novel of his is undoubtedly The Portrait of a Lady, which deals with the decisions that a young, innocent American lady makes when she is left a large fortune. Isabel Archer's choices come back to haunt her as she seeks to find a way to live the life she has chosen. However, two other favourites, which are novellas, and perhaps a bit more manageable, are The Turn of the Screw and The Aspern Papers. Both of these works are classic examples of the use of the unreliable narrator. The first gives us one of the most chilling ghost stories I have ever, ever read, and the second describes the lengths a man will go to in order to obtain copies of the letters of a famous poet, but also points towards what he may lose or gain through this obsession. Excellent. Certainly The Portrait of a Lady is a book I keep on coming back to again and again. Enjoy!
I would definitely say Jane Austen. Though I have read and enjoyed all her books, Emma really taught me a lot about how an author creates a character, not by what anyone says about her (or what she says about herself) but by her actions. And she is so delightfully imperfect!
I also love Jane Austen because she was living an ordinary woman's life (though unmarried) and still managed to write and write such beautiful work. Novels about everyday life, yet that captured such fabulous character studies. And finally, it is the longevity of her work; it is just as wonderful today as it was 200 years ago!
I'd have to say Cormac McCarthy. Besides being both talented and prolific, McCarthy has a style of writing almost totally unique in the modern literary world, and that's just something you don't find with too many authors anymore. Although his stories almost always have a dark theme to them, and expose the more sinister sides of human nature, the stories aren't hopeless. In the midst of them, if you're paying attention, there are some very hopeful messages too.
I also find his stories completely addictive. When I start in on one, I usually can't stop reading until I finish it. It's absolutely a great way to kill a weekend.
A close second as far as life impact for me would be Noam Chomsky.
It may sound a little bit shallow, but I would put Tom Clancy on the list. Not too many people consider his novels to be great literature, but I was always fascinated by the military and Clancy, more than any author I've read, has always done the research to know that the tactics and weapons he features in his books are in the right places and perform the right way. So many authors I've read have not done that kind of work.
The second I'd put on the list might be JRR Tolkien, his mastery of the construction of fictional worlds has always been astonishing. I have read the trilogy and just about anything else of his I can get my hands on and the depth of his creation has always blown my mind.