… so your list could be a mix of a books that got you into reading, an author that got you into reading a genre you never thought you’d read, a book that brought you BACK into reading
Harry Potter was probably a gateway book for a lot of people. The series has become so much a part of the fabric of my life that I don’t really remember what my reading life was like before Harry Potter, but I don’t think I read much fantasy then. I didn’t get involved in fandom or online communities until much later, almost after the books were all out, but Harry Potter was definitely my gateway into that.
Above Temptation by Karin Kallmaker was not actually the first lesbian romance I read, but I think it’s the book that got me hooked on the genre. It’s kind of a combination of action, intrigue, suspense, and romance, which seems to suit me well. Only after I read this book did I begin more frequently seeking out lesbian romance, and figuring out what appeals to me.
Malinda Lo, author of Ash, started me out on my YA queer characters quest. Her website has been one of my main sources of information, and really has introduced me to a lot of the issues around YA books and diversity. For example, see this page.
Gail Carriger was my introduction to steampunk with Etiquette & Espionage. I didn’t know it was steampunk when I picked it up (or I might not have tried it, under the mistaken assumption that I wasn’t interested in steampunk).
First Test, by Tamora Pierce, is a book I think of as defining my interests, though I can’t quite put the feeling to words. I read this book and Arrows of the Queen by Mercedes Lackey around the same time, and they feel like gateways to my teenage reading interests. I think I spent most of high school reading and re-reading Mercedes Lackey’s Valdemar books.