Quote Originally Posted by Big D View Post
Jenova = Sephiroth is a pretty through anti-theory I came up with some time ago xD I won't go into detail, but there's "evidence" to back it up

There's also an expanded version of that theory, whereby Jenova is actually Melkor/Morgoth, from Tolkien's fictional world.
Bolded part = pure awesome.

As for Jenova = Sephiroth, I actually always thought they were pretty closely correlated and, generally, the same being. Jenova is controlling Sephiroth for almost the entire game, after all.