1. Hyperion, by Dan Simmons.
A good friend of mine recommended this book to me when I was in college, and I was immediately hooked. I eventually read the entire series, which was one of the most powerful, engaging series that I've ever read. The first book, Hyperion, is like a science-fiction version of the Canterbury Tales. An unusual group of seven pilgrims gather aboard a tree-ship (a gigantic tree that also functions as a spaceship) to try to avert a terrible galactic war. They don't know why they have been chosen for this mission, to travel to a planet called Hyperion and confront a mysterious creature called the Shrike. On their journey, they decide to tell each other their stories, so they can discover their connections and learn why they have been chosen. Each story is beautifully written, and I found myself fascinated by all the characters.