What Was The First Science Fiction Or Fantasy Book You Ever Read?

We endlessly debate which science fiction and fantasy books make great entry-level reads for newcomers to the genre. But what was the first book you ever read? What book brought you into science fiction and fantasy, and helped to hook you for life?

Over at USA Today, they're asking a bunch of SF authors what was the first science fiction and fantasy book they ever read — so I thought it would be a good idea to ask you guys the same thing. Please include a book cover or some other representative image. And please include the title, the author, and what kind of impression it made on you. Thanks!

Top image: The War of the Worlds by H.G. Wells. Not 100 percent sure it was my first book, but it made a huge, crazy impression on my young mind. Also, Lloyd Alexander's Chronicles of Prydain.