The official position of the Spiral team is that Satoshi is a cat:

1) Never around when people want them to be.
2) Impossible to find when they don’t want to be found.
3) Eats weird gross food.
4) Proficient in C++, which has the number of characters as “cat,” starts with a C, and has a character that looks like a lowercase T.
5) Keeps weird hours.
6) Prefers English spelling because all cats have British accents.
7) What are cypherpunks if not mysterious? What are cats if not mysterious?
8) Independent and unknowable.
9) Whiskers, probably.
10) Could be sitting next to you and you wouldn’t know it.
11) Could be sitting on you and you wouldn’t know it.
12) Knows how to use a keyboard.
13) Very popular online.
14) Known to “move on to other things.”
15) Satoshi Nakamoto is a Japanese name. You know who eats a lot of fish? The Japanese. You know who else?