The Hitchhiker's Guide to the Galaxy, by Douglas Adams.
I bought this for my wife this past Christmas, because she's become such a huge Dr. Who fan (Adams was script editor during season 17), despite hating it when she was a child. This book is every bit as brilliant as many say it is...hilariously so.
My first exposure to "H2G2" was at age eleven when I stayed late at a friend's house watching the series on PBS. I didn't get all the high-falootin' concepts, but it was British, so that was something to young me.