The O'Neil Brothers are a family of inbred, hillbilly, redneck meth dealers in Blaine County. They are familiar with Trevor Philips, a drug and arms dealer also based in Blaine County with his own company, Trevor Philips Enterprises, whom the O'Neil Brothers are rivals with.
After some potential clients, the Los Santos Triads, decide to work with the brothers instead of Trevor, the O'Neil ranch is attacked by Trevor, who kills most of the family, save Elwood, Walton and Wynn, who left before the attack, and destroys their ranch by blowing up the meth lab in the basement.
- GTA V
- Trevor incorrectly lists Don (instead of Dan) as one of the O'Neil Brothers in "Predator". He also mentions a possible additional brother named Dalton though Elwood did not mention him in Crystal Maze. He may have meant Walton, however.
- Its unknown if the O'Neil Brothers has some kinship with Betsy O'Neil.
- When killing a O'Neil Brother in Crystal Maze, sometimes another one will say something like "Ned?! Ned?!", possibly another member of the O'Neil Brothers.