For a really excellent critique of the broader trope represented by the Fremen, I recommend the entertaining and informative post series The Fremen Mirage on the blog A Collection of Unmitigated Pedantry. The author describes the mirage as having a few components:

1. People in less settled or ‘civilized’ societies are made inherently ‘tougher’ by those hard conditions.
2. Consequently, people from these less settled societies are better fighters and more militarily capable than their settled or wealthier neighboring societies.
3. That, consequently the poorer, harder people will inevitably overrun and subjugate the richer, more prosperous communities around them.
4. That the consequence of the previous three things is that history supposedly could be understood as an inevitable cycle, where peoples in harder, poorer places conquer their richer neighbors, become rich and ‘decadent’ themselves, lose their fighting capacity and are conquered in their turn.

I think this is a common trope that's sufficiently ahistorical as to be misleading, which seemed worth flagging on a list of fiction for people thinking about possible long-run futures.

I recently read Star Maker by Olaf Stapledon after a conversation in which someone said that it inspired them to think about longtermism related ideas way before they had heard of effective altruism.

It covers a fictionalised history of the universe from the beginning to end, more like a documentary or a textbook than a novel with characters and plot. It's from the point of view of someone who is picked up from a hill in England and then moved around the galaxy and observes other civilisations in a variety of  times throughout the life of the universe.

It's written in 1937 and was said to inspire people like Arthur C. Clarke, Freeman Dyson and Jorge Luis Borges and includes speculation on civilisational unity and collapse, space exploration, metaverse, future technology, genetic engineering and existential risks.

Given the inclusion of space opera like Dune, I recommend including Vinge's work like A Fire Upon the Deep and A Deepness In the Sky. These deal with the long term consequences of intelligence explosion, albeit one in a world with slightly different physics than ours (or so it seems given our limited information; Vinge is careful to construct it in a way such that I think we can't be certain today our universe is not like the one he depicts in the books).

I'd also include Niven's Ringworld. Not obvious this is longtermist at first, but deep into the book that changes (not much more I can say without spoilers if you're hoping to read it).

Thank you very much for creating this list! 

Related, see the contributions in this thread. Books recommended there which you did not mention:

• Foundation
• The Mote in God's Eye
• Alas, Babylon
• On the Beach
• Canticle for Leibowitz
  
   

Would you mind me adding yours to this question? Or would you prefer to do it yourself?

RE: "Consider Phlebas, The Player of Games - Iain M. Banks"

I would second your ordering of PoG>CP. To add to the ordering: IMO "The Use of Weapons" is also not a really good book from a longtermist point of view, while "Excession" is a great read (so I guess: Excession>PoG>TUoW>CP).

I would be interested in what other people thought about the rest of the books of the culture series - are there some books that are much better than others?