In Pictures: The earliest days of your favourite s...
First Facebook profile: Mark Zuckerberg, early 2004
It makes sense that Facebook's founder would also have the site's oldest profile. Back before Facebook adopted user-chosen URLs, you could see that Mark Zuckerberg's Facebook ID was 4, meaning his current profile was the fourth created. Accounts 1 through 3 have vanished in the mists of time now; presumably they were test accounts, with (we hope) hilarious fake names attached to them.
In Pictures: The earliest days of your favourite social networks