Jed Stokely lived with his adopted father in New Haven until the day he decided to murder him and join the bandits; taking the name "Reaver". He is notorious even among the bandits for having a chip on his shoulder and daddy issues.
Reaver is the target in the mission Two Wrongs Make A Right. The Vault hunters solve the mystery surrounding the disappearance of Jed Stokely, and make their way to put an end to his wrongdoings.
In the original (unused) plot of Borderlands, Reaver is the man Roland swore to kill, a leader in the Brigadiers (the bandits). He initially mistakes Mordecai for him when they meet, since Reaver's attire and gear are similar. This would place Reaver in the position currently occupied by Krom.