Vampire: The Masquerade: A Storytelling Game of Personal Horror (3rd Edition)

I've always been a huge fan of the WoD role playing games, and even more so when you consider that they're all modular and you can mix and match elements from each system and make a storytelling experience something really grand. Vampire pretty much started my love of the series of games, and I've had the pleasure to start a group once again. The constraints and the wonderful power struggles, not to mention the possibility that a character can become very beast, makes the system very awesome.
(Note: This is the older system, not the recent re-creation of the same.) The amount of sourcebooks to enrich the storytelling makes this system preferable, in my opinion.

I had a lot of fun LARPing using this, but let's be honest, it is a very, very silly book. The pictures are bad and the writing is worse. Nevertheless, it is an excellent gateway drug into the world of gaming.

A friend gave me this role-playing game book in the early 90s. Although I never got into gaming, I totally dug the descriptions of the clans in the Masquerade.

This was the game that started White Wolf's rise as a major gaming company. Emphasizing role-playing over roll-playing, focusing on the personal that made player characters seem like real beings, and riding the tide of angst and goth, V:tM changed how games were written.