A former U.S. Marshal who reluctantly ends up as Sheriff of Eureka. Jack is consistently dumbfounded by the wonders Eureka produces, as well as their propensity to produce things which often threaten the entire town, if not the world. Jack's admittedly simplistic ideas and ability to make intuitive connections between seemingly disparate events often save the day.
Carter: Ok everyone calmly leave the cafe and away from main street
Carter: No idea, just do it.
Dr. Parrish: You're accusing me of something I might do?
Carter: Well when you put it like that.