Bill established his own gang after he left Dutch's Gang somewhere between 1899 and 1910. 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 after the Del Lobo gang.
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 accompanies Marshal Johnson and his deputies, but gets ambushed by the Williamson Gang when he returns Norman at Tumbleweed, and Norman dies in the gunfight. Marston and co. wipe 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. They use a Trojan horse strategy, where West Dickens presents his elixir to the outlaws, only for John to be hiding inside the wagon with a Gatling gun, which leads to the gang’s annihilation. Although the Williamson Gang was eliminated, including the reinforcements that attempted to retake the fort, Bill managed to escape to Mexico on the previous day with the help of Javier Escuella.
Marston later travels to Mexico in pursuit of Bill and Javier. Marston either kills or captures Javier, then kills Bill with the help of Abraham Reyes and his rebels after being betrayed by the Mexican Army.
After the Williamson Gang had gone from Fort Mercer, the Mexican Banditos would eventually take over, with lots of stolen money; Marston can clear them out with the aid of Leon Galindo in his travels.
The assault on Fort Mercer spelled the end for the Williamson gang, having lost all of its members, its hideout and its leader having gone into exile.
- Bill Williamson - founder and leader
- Norman Deek - second-in command
- Outlaw on Horse
- Outlaw in Brown
- Outlaw in Blue
- Wayne Daniels
- Seth Briars
- Harry Dobbing
- Irvin Pennick
- Rufus Starkley
- Elmore Vinnis
- Kent Gallaway
- Melvin Spinney
- Ralph Stricker
- Sid Winkler
- Quinn Malloy
- Zebedee Nash
- 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.
- Unlike most gangs, the Williamson gang doesn't offer the player an outfit. It shares this trait with Dutch's Gang. Most likely because Bill’s gang doesn’t have a set uniform and Marston’s default outfit is effectively a Dutch’s Gang outfit in and of itself.