Poll - are there any good prequels?

[jack]

This came up in the pub last night with the scifi society -- are there any good prequels, preferably scifi/fantasy? We thought of:

Children's books where the prequal is written second out of a series: Magician's Nephew, Charmed Life.
Series written out of order, such as Hornblower, Small Gods in TP.
Retrospective prequels: Asimov's robot stories became prequels to his foundation novels, though weren't at the time.

I decided that it's because prequels generally get written when an author (or their heirs) runs out of ideas, even more so than sequels, but if that's not the case they're by no means inherantly bad.

Can you think of any others?

Comments

[tienelle.livejournal.com]

Bujold's "Barrayar" books don't seem to be written in chronological order, so you could say that some of them were retrospective prequels to others. They seem pretty good.

Magic's {Pawn Promise Price} (Mercedes Lackey) were also prequels, and (I think) bloody good. The {Black White Silver} Gryphon, also prequels by the same author and in the same universe, were less good.