In the beginning, Roswell viewers thought the beautiful alien Isabel Evans was mean and tough, but Katherine never saw her screen alter ego in that way. "She is very guarded. She’s very loyal and devoted to Max and Michael. She loves being human, loves her parents and normal teenage stuff like going to high school and going to the prom."

In its second season, the show focused more heavily on the science fiction aspects and delving into the mythology of the alien teens, whose powers are growing stronger.

While Katherine has never been to New Zealand, she was thrilled to discover that Roswell is a big hit here. She says it must be the universal aspects of the show.

"What appeals to me about the show is that it ties in day-to-day teenage life, with some extraordinary story plots and ideas.

"Creating the mythology that goes along with these characters, and understanding their powers, kind of appeals to young and old all over the world."

Before Roswell, Katherine says she had never been interested in sci-fi. She never watched Star Trek or The X-Files, or sought out science fiction movies. "But once I became involved in the show, it created a whole other world to consider. I love the mythology of it," she says.

Away from Roswell, Katherine enjoys the simple pleasures in life – listening to David Gray’s new folksy CD, reading (most recently Memoirs of a Geisha, by Arthur S. Golden), and hanging out with her friends.

And she likes dating to be something really casual, like burgers and milk shakes at a cool diner, and just talking and getting to know each other. But, the burgers may have to be the healthy veggie kind. "As far as eating goes, I have a lot of restrictions, so I don’t eat a lot of dairy or wheat. I try to keep it very organic and very natural. But every now and then when I eat out I have a steak. I once ate 12 ounces of steak and a rack of baby-back ribs. I don’t know how to justify it except to say I am only human."

The stunning actress says that she knows she is a role model for young girls who love Roswell, and she feels a responsibility for them.

"The biggest thing I want all young women to know about themselves and about life is that they are unique and they are truly beautiful, no matter what," she says.

So what’s the best advice she has ever heard that she’d like to pass on to her fans?