Damn, you people just made me realize I have to read way more. For me it would have to be:
-Fahrenheit 451 by Ray Bradbury. I just fell in love with the idea, the characters and everything about it. It was the first book I read for pleasure and I still read it every year.
-American Gods by Neil Gaiman. I love fantasy, and the way Gaiman brought these Gods to life is just fantastic.
-Harry Potter (1-7) by J.K. Rowling. Yes it is mostly for kids, but it´s so enjoyble for anyone. The way Rowling made this whole new world of magic within our world is brilliant.
-The Dark Knight Returns by Frank Miller. It´s probably the best Batman story, and it is for a reason. Miller reinvented Batman and he did it in a great way.
-Sandman by Neil Gaiman. Another graphic novel where Gaiman brings to life the personification of dreams. It´s another fantastic read, even if you´re not into comic books. Honorable mentions:
Cloud Atlas by David Mitchell
The Hobbit by Tolkien
Watchmen by Alan Moore
V for Vendetta by Alan Moore
Transmetropolitan by Warren Ellis