Crackbone began appearing in episodes of the Youtube machinima series "The G-Man Sqaud" roughly around 2006-7 in the episode "Trams"

Followed by "Bored Meeting"

He's also appeared in the episodes "Christmas Special"

and in "Boris & Clyde"

Pretty soon, he began appearing in seperate videos of him playing different games.

Left 4 Dead

Zombie Panic

Not much is really known of Crackbone. As far as people know, he is Norwegian. No pictures of Crackbone surfaced until about a year ago. He is also responsible for creating the term "Brain Dawgs".

Crackbone competed in The Greatest Killer Zombie competition, where he lost to Stev

Crackbone has a fan made Facebook account, where people can follow him and worship him
http://www.facebook.com/pages/Crackbone/52083107161?v=info
Crackbone even had his own website, www.braindwags.com, but it has since been shut down (as far as we know):

Crackbone has a variety of catchphrases or habits whilst playing his games including:
"Cut 'Em Up!"
"You Can't Even Talk"
"Asshole"
"I Gotz Them Braindawgz"
Screaming Into The Mike
Laughing At Random Points
Insults Every New Person He Meets

In the G-Man Squad, it is shown he dislikes a portion of the squad, including Gerald, whom Crackbone picks on due to his sezual interests.