Zurich International Chess Tournament, 1953, by David Bronstein
Perhaps the best book on the middlegame ever written, the Zurich '53 book is Bronstein's magnum opus. Bronstein drew a match for the world championship against Mikhail Botvinnik.

A Guide to Chess Endings, by Dr. Max Euwe and David Hooper
Former World Champion Max Euwe covers the most important endings in his dry, objective manner. Reading this book elevated my end-game play from 1500 to 2000.

Chess Openings: Theory and Practice, by I.A. Horowitz
Simply the best one-volume opening manual ever published. The "Idea Variations" and "Practical Variations" are unique. Example games are top-notch - many by Fischer, Capablanca, Alekhine, Smyslov, Geller, Gligoric, Petrosian, Tal, Spassky, and other 20th century luminaries.

Chess Fundamentals, by J.R. Capablanca
Private chess lessons from Capablanca - What more could one ask for? Stay away from electronic or "revised" editions of this book. I did not post a link because it is hard to tell which versions are genuine. Get a vintage copy if you can.

500 Master Games of Chess, by Dr. Savielly Tartakower & J. Du Mont
This is probably the greatest single collection of games ever published. Games by Anderssen, Morphy, Blackburne, Pillsbury, Lasker, Marshall, Steinitz, Tarrasch, Alekhine, Capablanca, Spielmann, Tartaower, Rubinstein, Réti, Nimzowitsch, Euwe, Botvinnik, and many other masters. This is a great book for the cabin, for trips, or for any other occasion when you want to relax and play over the great games.

My System, by Aron Nimzovich
The great masterpiece of positional play by Nimzovich.

Lasker's Manual of Chess, by Dr. Emmanuel Lasker
An outstanding all-around Chess primer, by the former world champion Dr. Emmanuel Lasker.

The Game of Chess, by Dr. Siegbert Tarrasch
Steinitz was the founder of the classic positional school and Tarrasch is its chief exponent.