Marx-The Communist Manifesto
Even if you’re not a communist, it’s still an important book because it shows the inner-workings of capitalism. Not to mention that Marx had an influence on Barthes, Althusser, Foucault, and other philosophers.
Thoreau-Walden
I think it’s a good book to live by; simple living and self-sufficiency is something we should all strive for.
Eliade-The Sacred and The Profane
This book really gave me a deeper understanding of religion.