Dragaeran Empire novels by Steven Brust
In a world where being an assassin is a perfectly acceptable trade, the Dragaeran Empire controls most of the planet. Assassin Vlad Taltos is one of the minority races known collectively as "Easterners." In these novels he takes on all manner of thieves and cut throats and gradually learns more about the Dragaerans.
Dune series by Frank Herbert
In a universe ruled by emperors, a spice known as melange is priceless. Used to extend life, the spice also expands consciousness and is necessary for space travel. Only found on one planet, Dune, it is the cause of constant treachery and upheaval.
Books in the series by Brian Herbert:
Foundation series by Isaac Asimov
The Galactic Empire rules supreme. Outwardly profitable and healthy, it is actually in slow decline. One remarkable man, Hari Seldon forsees the fall and the thirty thousand years of dark ages that will follow. Seldon develops a branch of mathematics called psychohistory which can predict the future, but only on a mass scale. Using a set of "crises" over the centuries, he hopes to shorten the dark ages to a thousand years. The books in the series deal with the implications of this theory, the two Foundations he has set up to deal with the coming fall, and the crises which follow.
Petaybee series by Anne McCaffrey
On the icy planet of Petaybee, strange things happen. The sentient planet is a challenge for its inhabitants who fight to protect it from a powerful corporation bent on domination of its resources. Major Yanaba Maddock finds her loyalties tested as she learns to love the planet and its people.
Shannara series by Terry Brooks
The Great Wars of science almost destroyed an entire world. The world that remained replaced science with magic as a means to make new discoveries and acquire power. Gnomes, trolls, dwarves, and elves abound and a simple man, Shea Ohmsford, and his companions are pitted against the greatest power of evil the world has ever seen.