My question is this: What is the most popular, well known fanfic and/or
series of all time? The one that more people associate with fanfics than
all others. If you walk down the street, and ask the first person you come
across, "when you hear the word fanfic, what comes to mind?" And they
reply, "what's a fanfic?" So you continue your little venture until someone
gives you an answer, what is that answer? And who is the most well known
fanfic author of all time? And what happened to him?

Sadly, not an anime author.  Most people would answer Stephen Ratliff, if
only for sheer infamy.  At least net-authors.

--Sean Gaffney
--who apologizes for uttering the name Ratliff... :-)