Essentially, Goku's best friend, and the Kenny McCormic of the Dragon Ball Series, The one who's died the most times always to be wished back to life by the show's titular (funny word) Dragon Balls (equally funny word).
The poor bastard has died a grand total of four times throughout the shows:
Once in Dragon Ball (savegely beaten and murdered.)
Once by Freeza (completly vaporized.)
Once by Majiin Buu (though, who could blame him, since that was the time EVERYONE DIED.)
And finnally of natural causes at the end of DBGT (I can't believe I sat through the whole thing either.)
The only thing separating him from Kenny is that when he's killed, instead of shouting "OH MY GOD!!!! They Killed Krillin! YOU BASTARDS!!!" Goku beats the living tar out of anyone who does.
krillin's Japenese name is a pun on "cheastnut". Why didn't we americans just name him Chester? It's probably just me.