Dune by Frank Herbert
The first, and some say the best, of Herbert's DUNE series is the story of a young man's trials and realizations on a dessert world that holds the key to making extended life and space travel possible. Along the way he becomes a messiah to the indigenous people of the planet and emperor of the known universe. I've read this book about twenty times and each time I find something new in the overall story. This is a very complex narrative that earns my vote to be number one in Science Fiction.
A Stranger in a Strange Land by Robert A. Heinlein
A human raised by Martians comes back to Earth, inherits a fortune, is mentored by an author that sounds a lot like Heinlein himself, and founds a religious movement. Throw in some interesting concepts, such as free-love and "thou art God", and you have a very interesting read. It was controversial when it first came out and still turns heads today. Look for edition that was published after Heinlein's death for materials not found in the original.
The Hitch Hiker's Guide to the Galaxy by Douglas Adams
Need a break from serious science fiction? This book is for you. Follow the adventure of Arthur Dent and his pal Ford Prefect as they get into one spot of trouble after another. It all begins with a hyper-spacial bypass being constructed and Earth is in the way. Ford reveals that he is an alien and rescues Arthur from the planet just as it blows up. And that is when Arthur's problems really begin. The best features of this and the rest of the "Guide" series is the Guide itself. Little tidbits about the galaxy our intrepid duo are traveling about in are summed up for us via the Guide. Hilarious, poignant, and insightful. This book will keep you in stitches.
Ender's Game by Orson Scott Card
Earth is almost wiped out by an alien force and mankind barely beats them back, so what can the government do to win the war against the invaders? Well, for starters, you look for a child genius, snatch him away from his family, put him in an orbital military academy and set him loose playing games. Well, that's the bare gist of the book. But, the lessons Ender Wiggin learns along the way are what hold the keys to Earth's victory. This book, never meant to be a coming of age story, has none-the-less become one to many.
Foundation Isaac Asimov
This is actually a trilogy, but since you can't really get the feel of it without reading all three, that's ok. That's what omnibus versions are for. This is the story of the decline of a twelve thousand year Galactic Empire and one man's vision to preserve the total sum of all human knowledge when mankind descends into ignorance, barbarism, and warfare. He convinces the greatest minds in the galaxy to gather at a remote planet he calls the Foundation in hopes of providing a haven for the knowledge mankind has learned and can be rekindled when the dark times are over. These books tell of the struggle for the Foundation to survive during the thirty thousand years of darkness the founder of the Foundation envisioned.
I couldn't narrow it down to just five books, so here are the one's that I had trouble not mentioning. I'll come back to the authors of these books in future posts.
Neuromancer William Gibson
1984 George Orwell
I, Robot Isaac Asimov
The Time Machine H.G. Wells
The Martian Chronicles Ray Bradbury