Ask Lemmy

The Jungle. Coal. Ubik. Catch 22. HHGTTG.

The Crying of Lot 49 — it's pretty short.

Crime and Punishment by Fyodor Dostoevsky. For me, I think Russian literature is a must-read.

The Count of Monte Christo, Fahrenheit 451, Neuromancer.

The Art of UNIX Programming by Eric S Raymond. I’m only half-joking; I used to read it when I had insomnia because it was equal parts fascinating but verbose enough to get me to sleep.

Otherwise Waking Up by Sam Harris. I’d only heard of him after a group meditation session which I’d never done before and immediately became hooked: that you could be spiritual without religion was an entirely new concept for me.

To kill a mockingbird -Harper Lee

After reading it, I felt I had read and understood something important that remained with me. Not a difficult or long book, enjoyable and interesting.

The Maxims of Ptahhotep. First book we know of & filled with practical advice.

Socialism: Utopian and Scientific by Friedrich Engels. Short, yet clearly elaborates on the shift from earlier utopian views of socialism of figures like Robert Owen to the scientific socialism of Marx and Engels. One of the best explanations of Marxism itself, other than the essay Principles of Communism. It was taken from the larger and more comprehensive Anti-Dühring as it was believed to be an excellent work for propaganda purposes (and this judgment proved correct, as the booklet spread like wildfire).

Honorable mentions go to Capital, Volume I by Karl Marx, Imperialism, the Current Highest Stage of Capitalism by Lenin, The Wretched of the Earth by Frantz Fanon, and Neocolonialism, the Last Stage of Imperialism by Kwame Nkrumah. This series of books expands on capitalism during its beginning, intermediate, and imperialist phases, and imperialism itself in its beginning, intermediate, and final phases as they relate to colonialism and neocolonialism.

The Tragedy of the Moon by Asimov.

Edit: And one more because why would be only one?
A Short History of Nearly Everything

I think you'd have to pick something more geared towards children as books for older people will potentially be too narrowly focused or infused with cultural or regional influences.

Something like the giving tree has some good staying power and discuss concepts that should be beneficial across time/cultures/religions.

A Brief History of Time

A short history of nearly everything - Bill Bryson

For Americans I think "slavery by another name" and "bury my heart at wounded knee" should be required reading.

Don't really know one book that everyone should read, maybe everyone should read more than one book

Ishmael by Daniel Quinn

Hagakure.

Timequake by Kurt Vonnegut Jr. I'd have never picked it up if I hadn't been bored and trying to kill time, but it really put life in a new perspective. Genuinely think it's made everything lighter since reading that one.

The Remains of the Day by Kazuo Ishiguro

Absolutely beautiful book

Surface Detail by Iain M Banks

Part of The Culture series but can be read standalone, potential for being one of the best hard scifi books out there