Where are the collaborative novels?

Someone asked me the other day whether a corporation could run for president. I said no. The closest to that would be The Space Merchants. And that that made me think . . . where are the collaborative novels? I’m not talking about ghostwriters, or about that book by James Patterson and Bill Clinton (which I assume had a third collaborator who actually did the writing). I’m talking about actual collaborations. Other than The Space Merchants (and a couple other books by those two authors), the only example I can think of offhand is The Gilded Age, which I’ve never read cos it’s not supposed to be so great.

There’s lots of collaboration in drama: plays, movies, and of course TV. Why no collaborative novels? Or maybe there are some that I can’t think of? I can understand that novelists usually like to work alone, but, still, given how many excellent novels have been written, I’d think there’d be a few more that were built in collaboration.

This is buggin me.

P.S. I guess you could call Huckleberry Finn a collaborative novel in the sense that your closest collaborator is “you, X years ago,” and so Twain in finishing that novel was collaborating with his past self. (The last half of that book was written several years after the first half, and many critics think the second part is worse.) But here I’m looking for collaborations between two different people, yielding a novel that is considered to be important or of high quality.