Eureka is an American science fiction television series set in a town inhabited almost entirely by geniuses. In the UK, the show is known as A Town Called Eureka. It was announced on July 24, 2009 that the show had been picked up for a 22 episode fourth season,set to air in mid-2010.
Eureka takes place in a high tech community of the same name, located in the state of Oregon in northwest America and inhabited entirely by brilliant scientists working on new scientific advancements. The town is operated by a corporation called Global Dynamics (GD), that is overseen by the United States Department of Defense. The town's existence and location are closely guarded secrets
U.S. Marshal Jack Carter stumbles upon Eureka while transporting a fugitive prisoner (his own rebellious teenage daughter Zoe) back to her mother's home in Los Angeles. When a faulty experiment cripples the sheriff of Eureka, Carter finds himself quickly chosen to fill the vacancy. Despite not being a genius like most members of the town, Jack Carter's ability to connect to others, his simple but effective ideas, his above average intelligence in practicality, and his steadfast dedication to his work repeatedly saves Eureka, and sometimes the entire world, from one would-be disaster after another
- Sheriff Jack Carter (Colin Ferguson) is a 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 that often threaten the entire town, if not the world. Despite being an average man in a town full of geniuses, Jack's admittedly simplistic ideas and ability to make intuitive connections between seemingly disparate events often save the day. (This is in contrast to the other residents of Eureka, who, being stereotypical scientists, tend to over-complicate things and get lost in minutiae). Jack has deep feelings for Dr. Allison Blake, although his reaction to new arrival Dr. Tess Fontana result in a blossoming relationship. However, by the end of Season 3, the situation once again changes and at the end of the season finale, we find Carter at a crossroads with an important decision to make which could impact upon his relationships with both Blake and Fontana...
- Dr. Allison Blake (Salli Richardson-Whitfield) is a Department of Defense agent who acts as the liaison between Eureka and the Federal Government, and later becomes the director of Global Dynamics. She is always at the forefront of any dilemma which might arise.
- Tess Fontana (Jaime Ray Newman) is described as a "brilliant engineer and astrophysicist who sees things differently than those around her... putting her at odds with the mainstream scientific community." Allison, having known this out-of-the-box thinker since Grad School, puts her to work on a highly confidential Global Dynamics project. By the last quarter of Season 3, Dr. Fontana finds herself spending time with - and eventually positioned as a love interest for - Colin Ferguson's Jack, although the Season 3 finale indicates that her character is to be written out from the primary storylines in Season 4.
- Zoe Carter (Jordan Hinson) is Jack's rebellious teenage daughter. Unlike her father, she is intelligent enough to keep up with the town's residents (her IQ is 157), yet like her father, possesses the street smarts most of the town's residents do not. She longs to be a medical doctor, and with the help of Henry's recommendation letter, receives an early acceptance to Harvard's medical program. She dates Lucas.
- Dr. Henry Deacon (Joe Morton) is the town jack-of-all-trades. Although, like most residents of Eureka, he is a brilliant multidisciplined scientist, Henry has ethical objections to the kind of research conducted at Global Dynamics, preferring employment as the town's mechanic. Henry's assistance is often invaluable in defusing the situations the experiments in town create. He was destined for incarceration, following a false biohazard scare to distract him from trying to free Allison's son (Kevin) from the Artifact leading to the escape of Beverly. However, he was eventually granted a reprieve and remained in Eureka. During Season 3, he was elected Town Mayor as a write-in candidate
- Dr. Nathan Stark (Ed Quinn) is one of Eureka's top scientists who is modeled after Tony Stark. He and Jack are frequently at odds, though both respect the other. He was formerly married to Allison, and they rekindled their relationship in the second season. They were supposed to get remarried in the third season, but he died whilst saving the world from a time paradox on the day of their wedding.
- Deputy Jo Lupo (Erica Cerra) is another of the town's few non-genius residents. Jo is a tough, no-nonsense cop with a love of firearms. From Season 2 onwards, after a brief fling with Taggart, she later develops a relationship with Zane.
- Dr. Douglas Fargo (Neil Grayston) is a junior scientist who is treated somewhat dismissively by his peers. Accident prone, he more often than not ends up a victim of the disasters that befall the town. He has also caused a fair share of the problems.
- Dr. Beverly Barlowe (Debrah Farentino) is the town psychiatrist who secretly works for a conglomerate of business interests wishing to exploit Eureka's innovations.
- Dr. Jim Taggart (Matt Frewer) is a somewhat eccentric animal expert.
- Vincent (Chris Gauthier) is the owner of Cafe Diem. He prides himself on being able to make anything his customers ask for — partially due to the extradimensional features of his pantry, which essentially allows him infinite room in which to store ingredients for recipes. He is no exception to the town's geniuses and holds a Ph.D. in Molecular Gastronomy. His last name has not yet been revealed.
- Zane Donovan (Niall Matter) is a rebellious genius, recruited in the second season as an alternative to imprisonment after being arrested for fraud (allegedly causing the New York Stock Exchange to crash). He also develops a relationship with Jo Lupo shortly after his arrival in Eureka.
- Eva Thorne (Frances Fisher) is a corporate fixer hired to make Eureka more profitable, which she mainly accomplishes by downsizing. She seems to have an ulterior motive involving an underground military base built before Eureka was founded. An accident in this facility resulted in her being extraordinarily long-lived - she is revealed to be around 100 years old when she returns to Eureka. After sacrificing her one chance of finding a cure in order to save Zoe, Thorne leaves to start a new life finally able to put her past behind her.
- General Mansfield (Barclay Hope) is an army general who frequently visits Eureka to check up on Government projects, or to enforce martial law when experiments get out of control.
- Lexi Carter (Ever Carradine) is Jack's free-spirited sister who comes to live with him and Zoe early in Season 3 after finding out she (Lexi) is pregnant. Her fanatic emphasis on waste management, recycling, spirituality and politics quickly endears her to others and makes her an asset to the community.
- Lucas (Vanya Asher) is Zoe's shy genius boyfriend. They start dating after being forced to work together on a high school science project in Season 2. In Season 3, Lucas is cited as having the third highest IQ ever measured, even though he can be a bit of a klutz. He receives early acceptance to MIT after a letter of recommendation from Henry, so he is able to be with Zoe in Massachusetts.