This is by no means intended to be an exhaustive list, but rather to give the philosophy student a starting point. Our best advice is that if you find a philosopher whom you like, find more books by that author.
The Western Tradition
General Reference Works
Audi, Robert (ed.). Cambridge Dictionary of Philosophy.
Copleston, Frederick. A History of Philosophy (in nine volumes).
Edwards, Paul (ed.). The Encyclopedia of Philosophy (in eight volumes).
Jordan, James N. Western Philosophy: From Antiquity to the Middle Ages.
Reese, William L. Dictionary of Philosophy and Religion: Eastern and Western Thought. New and Enlarged Edition.
Waithe, Mary Ellen (ed.). A History of Women Philosophers (in four volumes).
Great Works in Chronological Order
Freeman, Kathleen (ed.). Ancilla to the Pre-Socratic Philosophers.
Kirk, G. S., J. E. Raven, and M. Schofield. The Presocratic Philosophers. Second Edition.