Authors I've read

Copying nothings, here's a list of authors I've read 10+ books by, in no particular order:

Robert Heinlein
Piers Anthony
Katherine Kurtz
Philip José Farmer
Roger Zelazny
L. Ron Hubbard (yes, I read all of Mission Earth)
Anne Rice
Larry Niven
Michael Moorcock
Edgar Rice Burroughs
L. Frank Baum
Sir Arthur Conan Doyle
Franklin W. Dixon (the Hardy Boys books—yes, I know this is a composite pseudonym, but I'm still counting it)

There might be more, but that's what I can think of from a scan of my bookshelves. Notable near misses would be Robert Anton Wilson with 9 (three Illuminatus trilogies) and Iain (M.) Banks—I own 9 of his books but I've only read 5 so far. There are also plenty of authors who haven't written 10 books but I've read all or most of what they have written, including Douglas Adams, J.R.R. Tolkien, F. Scott Fitzgerald, Bret Easton Ellis, Jay McInerney, Douglas Coupland, William Gibson, Neal Stephenson, and J.K. Rowling.