#1: Dune (Frank Herbert)
Science Fiction doesn't get much better then this. Dune is every Science Fiction aficionado's wet dream. Many people claim Dune is Science Fiction's answer to "Lord of the Rings" and I have to agree: it sure is. There are many good science fiction books, but Dune is indeed a giant among giants. It truly is a pinnacle of Science Fiction literary achievement. If you haven't read Dune, doesn't waste any more time. Read it now!
# 2: Starship Troopers (Robert Heinlein)
War is beautiful according to Robert Heinlein. This is a novel about the glorification of war. The premise: space-marines wearing special armor battle vicious alien insect aliens. This is classic "old school" science fiction at it's best. It's a rip-roaring ride through the galaxy that you don't want to miss.
#3 : Ender's Game (Orson Scott Card)
This is one of the corner stones of science fiction and one novel that you shouldn't miss. A critique on society, the story of a boy who refuses to give up, a battle to save the fate of mankind - this science fiction book combines them all into one addictive and compelling mix that shouldn't be missed.
#4: Foundation (Isaac Asimov)
This is undoubtedly on of the finest works of science fiction ever written. If you a fan of science fiction with grandiose and epic storylines, get your hand on this book.
A corollary: Foundation is a series for people who love grand and complex ideas. If you are looking for a book heavy on the action but thin on concepts, this may not be the book for you. The strength of the ideas presented are the focus of this story, not the characterization. Regardless, this is one of those Science Fiction books that you just need to read. You will never think about Science Fiction the same way after reading the Foundation series.
#5: Snow Crash (Neal Stephenson)
Part-time hacker and pizza delivery boy and full time samurai swordsman, meet Hiro Protagonist. Snow Crash is breath taking novel with action and pacing thick enough to drown in. Snow Crash redefined and rejuvenated the Cyberpunk genre. If you want a novel with bucket loads of action, futuristic technologies ala The Matrix, and the gritty futuristic dystopia of the Blade Runner world, Snow Crash is the perfect recommendation.
#6: Forever War (Joe Haldeman)
The Forever War is pretty much The Vietnam War in space. It's brutal and bloody and makes a strong case that war really is pointless. Don't let the strong political statement of the novel deter you, however; this is Science Fiction at its finest: a complex, disturbing novel that makes you think...and feel. It's a great science fiction story that you don't want to miss, a true masterpiece of the genre.
#7: The Night's Dawn (Peter Hamilton)
This is space opera science fiction done right: Massive space battles, a large cast of compelling characters, political tension between planets, and an all out grand adventure. There is a good deal of space opera in the science fiction genre already, but Peter Hamilton is one of the best character writers in the genre and his plots are just so damn interesting. He really knows how to write a rip-roaring adventure that keeps you up into the late hours of the morning. Those in the mood for something big with lots of action, both in and out of space, Night's Dawn trilogy delivers.
#8: Gap (Steven R. Donaldson)
This disturbing series is a dark ride into hell that you don't want to miss. It's one of the darkest set of books I've read, period. But the world that Stephen Donaldson draws is superb. Stephen Donaldson is an author that cares deeply about characterization, and he excels at crafting anti-heroes. If you are looking for some dark space opera, I highly recommend the Gap series.
#9: Otherland (Tad William)
Those looking for something like the Matrix in written form need look no longer. Otherland is about as close as you'll get. With less mumbo jumbo psycho babble and more realism, Otherland makes for a really compelling read. Otherland starts slow, but those willing give it a chance will be greatly rewarded.
#10: Altered Carbon (Richard Morgan)
This is one dystopian cyberpunk with a lot of style and some seriously punishing action. I guarantee that once you start reading this novel, you won't be putting it down. Morgan is a man with some visionary ideas; he always has interesting characters, twisting plots, and heart-pounding action. Those that love Blade Runner, Snow Crash, and Neuromancer are in for a treat.