Jack Clayton is the administrator of City 18. He is a huge contributor to the building economy in City 18 and its neighboring cities (such as City 17) in the aftermath of the Combine's defeat. He is the husband of P-Body.
Much of Jack's past history is unknown, except that he was a wealthy property developer before the Seven Hour War. In the aftermath of the Uprising and the downfall of the Combine, Jack invested in the rebuilding of city 17 when much of it was destroyed. Jack then began expansion across the other Combine cities and became a national figure in rebuilding the economy.
In 2011 Jack had held a campaign against the criminal organization the Clandestine Company who were attempting to revive the Combine.
In City 18 Jack was murdered by the Clandestine Company. His daughter Emile Clayton was taken in by Nathan.
- He uses a modified Wallace Breen model.