From Eliezer Yudkowsky’s work-in-progress, Three Worlds Collide, a tale of the Prisoner’s Dilemma and other moral/logical conundrums:
I suspect the aliens will consider this one of their great historical works of literature, like Hamlet or Fate/stay night —
Well, I’d've said Haibane Renmei, but OK.
[Update: In comments, Yudkowsky chides that he meant the visual novel (i.e. comic, known in Japan as manga), not the anime. Regrettably, I did not know which one he meant, because not being a member of the culture of which he writes, I don't keep up with manga. I'm hard-pressed to believe it's as good as HR, but maybe I need to give it a look.]
[Update 2: *sigh* No, not the manga, the interactive version that allows you to make plot decisions. English versions for at least some of the main narrative pathways seem to be available; I guess I'm going to have to give them a try.
[I just read chapter 3/8 of Three Worlds; strongly recommended. One of the more inventive, entertaining, and provocative how-aliens-might-think stories I've seen.]
[update 3: Added the "culturally well-rounded" link.]
For those unfortunates who don’t know: Haibane Renmei is the single best work of the Japanese animation form known as anime, head and shoulders above everything else out there. This ought to be on everyone’s must-see list, even if you don’t know about, or actively dislike, anime in general. Fate/Stay Night is another anime; I’ve watched it, but honestly remember nothing about it; I suspect Yudkowsky is making a bit of joke here. I rate most anime on a scale that expands the 0-5 range of my normal ten-point movie/TV rating scale. HR easily rates eight, possibly as high as nine, on my normal scale. It is one of my favorite stories in any medium, and only loses a point or two because its low-budget creation limited its visual implementation. No, don’t read any summaries or reviews; one of the great pleasures of this story is the way it reveals itself to the watcher; the less you know going into it, the better. That said, commit yourself to watching it twice, at least — a great deal that passes unnoticed on first viewing will glow and hum with meaning the second. Watch it the first time with the English dub, so the subtitles don’t distract you; it has one of the better English dubs out there. Second time, savor the wonderful Japanese performances.
Dead serious here: Anybody who considers themselves culturally well-rounded should see Haibane Renmei. It’s as important as, say, The Seven Samurai.
In spoilers, the image that originally drew me in to the world of the Haibene:Show ▼