''Buffy, in this incarnation, is over.''
With those words, Sarah Michelle Gellar drives a stake into the hearts of ''Buffy the Vampire Slayer'' fans everywhere. After seven years -- five on The WB, the last two on UPN -- the young ''Scooby-Doo'' star (a.k.a. Mrs. Freddie Prinze Jr.) is leaving the cult pop sensation that made her a household name. Says Dana Walden, president of Twentieth Century Fox Television, which owns ''Buffy'': ''It would be difficult to overemphasize Sarah's value to the show.'' Adds ''Buffy'' creator Joss Whedon: ''There've been times that we didn't get along. There have been times when we've palled around. But no matter what, she was the other half of 'Buffy.' In seven years, she never let me down.''
Gellar is moving on, but plans are afoot to keep the lucrative franchise alive. Whedon is developing a spin-off that may involve current ''Buffy'' regulars and will be pitched first to UPN. ''It will be a completely different animal,'' he says. The good news for fans: Gellar has promised to make occasional guest appearances on the spin-off. The bad news: The spin-off will not be based around sexy bad-girl slayer Faith, played by Eliza Dushku, who is committed to a Twentieth Century Fox pilot directed by Phillip Noyce.
''Buffy'' will end with a five-part story that will see the return of Faith, some surprise deaths, and in the final episode, an appearance by a certain Angel. ''We're gearing up to tell a fabulous, huge, great arc,'' says Gellar. ''It's going to be pretty spectacular.'' Gellar herself is girding for many tears during production of the last episode. It was tough enough for her to keep a dry eye during this, her first exit interview. Popping chocolate-covered raisins as she spoke to EW in a trailer decorated with fan-drawn ''Scooby'' art, Gellar made us a bet: ''Ten bucks says I go home and cry when you leave.''