>>7Misuto, Thanatos, Insertnamehere, Tsuki, Firo, Enni, Bacurik, Satou, Kaori and Lurksalot are the ones who would probably be most well known.
Site was launched 06-19-2010 officially, according to the update page. The about pages and such were altered on the 29th, but they were altered primarily by user input, after a few days... So most of the aforementioned people joined in the first 10 days of the site's launch.
It really has been just about three years since then. There's been a whole lot of history and memories packed into them, too.
The next generation of people like Mael came a bit later. And then technically third generation like Divineraccoon and Forte Sigma joined maybe a year and a half or so after launch?
I remember they really stood out during a thanksgiving/octoberfest holidays when we were dealing with the worst influx of idiots the sight had seen at the time. They got really involved from there on, but I'm not sure what happened to them - Forte pops up occasionally.
Oh, and Juniase was the first black guy to join BBS. He joined back during the beginning too, but I don't think a lot of people remember him. He was all sorts of fun, I remember he was the first black guy because we ended up with a constant gag of him calling us all racist and telling us to get out (of the chatroom, thread, forum, etc.)
"Get Out." was pretty much his catch phrase. Then he got hit by a car. Then later hit by a truck. And later hit by a boat. Vehicles find him attractive.
There's also Bakyura, Juumonji's Cocoa, Irk and ScyRan. I don't remember much about Bakyura or Juumonji besides them posting often in the early days.
Irk and ScyRan are still around though - Not sure if they really count as well known.