Bill established his own gang after he left Dutch's Gang, not long after the botched robbery in 1906. The gang quickly rose to prominence in New Austin gaining a reputation as the most dangerous gang left in the west. By 1911, Bill and his gang took over Fort Mercer in Rio Bravo.
Red Dead Redemption
Bill and his gang later raid Ridgewood Farm killing men and raping many women that live there, but there are a few survivors. Marston, Marshal Leigh Johnson, and the Marshal's posse rescue the remaining survivors at Ridgewood Farm, then chase Williamson to Mercer Station, but he flees. The posse is, however, able to successfully capture Bill's second in command, Norman Deek.
After Deek's capture, Outlaw on Horse, a member of the Williamson Gang, arrives at the sheriff's office in Armadillo explaining that Bonnie MacFarlane has been captured and will be hanged if they don't return Norman Deek at Tumbleweed. Marston gets ambushed by the Williamson Gang when he returns Norman at Tumbleweed, and Norman dies in the gunfight. Marston wipes out the remaining Gang members at Tumbleweed and rescues Bonnie.
Marston later recruits seven people to help him assault Fort Mercer and the Williamson Gang. The Williamson Gang was then eliminated, including the reinforcements that attempted to retake the fort. Bill managed to escape to Mexico with the help of Javier Escuella.
After the Williamson Gang left Fort Mercer, the Mexican Banditos took over with lots of stolen money; Marston can clear them out with the aid of Leon Galindo in his travels. Marston later travels to Mexico in pursuit of Bill and Javier. Marston kills or captures Javier, then kills Bill with the help of Abraham Reyes and his rebels after being betrayed by the Mexican Army.
After Bill's death, the Williamson Gang effectively disbands, having lost its hideout, its leader, and most of its members.
- Bill Williamson - Leader
- Norman Deek - Second in Command
- Outlaw on Horse - Member
- Outlaw in Brown Suit - Member
- Outlaw in Blue Suit - Member
- Wayne Daniels - Member
- Aside from the above listed members, the Williamson Gang is primarily made up of unaffiliated criminals. Many of the outlaws encountered alongside Williamson are also bounties, and two (Harry Dobbing, and Irvin Pennick) are listed as members of the Bollard Twins Gang or unaffiliated.
- This gang, along with Dutch's gang, doesn't offer an outfit.