ET has your Cylon scoop!

The end of a space odyssey is close at hand as the fourth and final season of "Battlestar Galactica" premieres on Friday, April 4 at 10:00 p.m. on SCI FI. So who better to discuss the series' swan song than sexy KATEE SACKHOFF, whose recently resurrected character, Lt. Kara 'Starbuck' Thrace, has met her end once before!

"It is sad," Katee says of moving on. "I'm really going to feel the pain of it until the very end." Fans of the show will surely sympathize, but they also have pressing questions about season four. Namely: Do Katee or her fellow cast members have any theories as to who the final, dreaded Cylon is?

"We do [speculate] about it sometimes," the actress tells ET, "but as far as who it is, I don't think any of us will know for sure until we see it on television." The other four actors who recently learned their characters were secretly Cylon had a hard time stomaching the news, she says. "I still think MICHAEL HOGAN [Colonel Saul Tigh] hasn't come to terms with it."

Meanwhile, what about those mysterious season four billboards depicting the cast in a "Last Supper" pose? Are there, in fact, secret messages or a "magic eye" puzzle hidden within it?

"The plastic sheath with Anders is interesting," Katee admits. "And the fact that they made Tricia the messiah is pretty interesting, too … I wish I knew what they [the show's producers] were thinking."

The beginning of season four finds Starbuck "very fragile" and "extremely lost" as she leads the surviving human race to planet Earth. Looking back, Katee says she sometimes dealt with acting challenges that left her feeling a little lost, too!

"I would say that the sex scenes are a lot harder than I think anything that I've ever had to do on the show," she confesses to ET. "It's not natural -- it's just odd, very odd. It makes you kind of feel cheap. Like you're being paid to, or being allowed to in a sense, cheat on your significant other. It's very weird."

But when "Battlestar Galactica" finally powers down, Katee says her journey will have been a gratifying and momentous one: "What was so interesting about our show is that we never relied on the science fiction of the show to drive the show. We relied on the drama and the human condition and those really important questions ... So, I think that it kind of opened doors in science fiction to realize that."