Quick fantasy / SF question

I'm looking for examples of books where a work or a series, which was apparently complete, is followed up by more works after some time.

What I don't want is sequels by other hands, share cropping, "based on an idea by," continuing series, etc.

Examples I have so far are the later Earthsea books and Hal Clement's "Needle" and "Through the Eye of a Needle"

Can anyone suggest more examples?