Oh man I just found out about this

[Megamannt125]

In a director's cut sort of thing, a unnamed shinigami comes to talk to Ryuk, where Ryuk tell's the story of Light, now i've heard crappy theories about this shinigami being L, but I found a much better one:

He's wearing a coat, has red eyes, an evil smile, and something red around his head (maybe a...Tie?)
He gives Ryuk an apple also, and leaves before Ryuk finishes the story
He also has a scythe, similar to a scythe that Light holds in artwork...

(from the manga, the anime version of this conversation is different)

Light: "But you know what? If I did end up making those kinds of deals, I'd end up becoming a Shinigami just like you."

Ryuk: "There's nothing to worry about there. Light, you're already a fine Shinigami."

 

[coffeebean!]

So wait, is the shinigami L or Light?

 

[Megamannt125]

So wait, is the shinigami L or Light?

Light, only dumb people think it's L because he walks like L, but all shinigami walk like L.

 

[coffeebean!]

So wait, is the shinigami L or Light?

Light, only dumb people think it's L because he walks like L, but all shinigami walk like L.

The apple thing kind of gives it away :T

But wha-?
Director's cut :l