*U.S. Marshall Jack Carter (Colin Ferguson) is sharp and charming, with a quick wit and a street-smart edge. Dedicated first and foremost to his career, a recent separation from his wife has left him at odds with his teenage daughter, Zoe, whose brushes with the law keep Carter nearly as busy as his day job. In fact, Zoe's latest escapade has Carter transporting her home in his custody when their car crashes outside the town of Eureka, ultimately leading to his "promotion" to town sheriff.



Allison Blake is the government liaison between Eureka and the Pentagon and the head of Global Dynamics, an advanced research facility responsible for all major technological breakthroughs for the last 50 years. Charged with reporting on the progress of Eureka's citizens as well as their temperamental innovations, Allison grapples with an endless stream of crises and moral dilemmas.



Nathan Stark is a Nobel-prize winning mathematician, Eureka's head researcher and Allison Blake's ex-husband. Charming to a fault and keenly brilliant, he gives Jack Carter a run for his money in the contest for Allison's romantic interest, but Stark's professional desire to push the boundaries of science eventually compromise his personal integrity.



Josefina "Jo" Lupo is Eureka's deputy sheriff, a New Jersey girl and former U.S. Army Ranger. The eccentric residents of Eureka try her patience, but they've grown accustomed to her bluster and appreciate her dedication to their safety. At first, Jo is resentful of having to report to an outsider when Jack Carter is given the sheriff's job, but she comes to gain respect for his talents and becomes his trusted partner in maintaining the peace.



Henry Deacon is a true jack-of-all-trades. Masquerading as the local mechanic, his feats of engineering are a constant source of wonder and amusement. Whether outfitting Eureka's police cruisers with the latest and greatest gadgets or inventing a global air-conditioning system, Henry has the keen ability to figure out the mechanics of nearly any contraption. So why is Henry such a dedicated do-gooder? Perhaps he sees his work in Eureka as a chance to redeem himself for the sins of a mysterious and complicated past.



Douglas Fargo is the funny, lovable and put-upon executive assistant to the director of Global Dynamics. Blessed with great intelligence but cursed with terrible luck, Fargo seems forever stuck in his subservient role, even as his pet projects showcase his unlimited potential. Fargo's inability to control his curiosity frequently lands him in trouble, much to the chagrin of his disapproving mentor, Nathan Stark.



Zoe Carter is Jack Carter's defiant, delinquent, and also terribly intelligent daughter. Though Zoe tries to keep up her "riot grrrl" image, behind her attitude and piercings she's just another young woman who wants her absentee father to pay her some attention. And what's the best way to attract a cop's attention? Consistently put oneself at odds with the law—something that Zoe has become quite adept at doing.

*Character Summaries from Eurekapedia*