What are some particularly good animated science fiction films?

Cowboy Bebop, but watch the series as well. It’s one of the best animated Sci-Fi shows (and movies) I’ve seen. Akira, and Ghost in the Shell are also highly praised, though I didn’t like them quite as much. Howl’s Moving Castle was excellent but it’s not really futuristic Sci-Fi. It’s more retro-futuristic steampunky.

Iron Giant?

I always enjoyed Treasure Planet, even though it apparently got abysmal reviews.

Evangelion. Seriously.

The Girl Who Leapt Through Time. It has humour, romance, whimsy… it’s awesome and I am not in the mood to watch it again

The Iron Giant makes me teary-eyed.

Heavy Metal was pretty cool

Akira is really awesome.

Dennou Coil.
Ghost in the Shell.

Fantastic Planet but you already knew that.

Titan A. E. isn’t too bad – good story, attractive art (though the kangaroo aliens are a bit much).
Disney’s Atlantis may or may not count, depending on how much of Verne’s stuff you call science fiction.

try all studio ghibli films!!! they are the best! they are not per se sci-fi, but they are good animated films. to be exact, try the SPIRITED AWAY studioghibli film ;)

Try Renaissance honey, its wonderful, I watched it because Danial Craig does one of the voices, but I’m glad that I did, good stuff.

Yesss, Akira is amazing.