Buffy's werewolf friend "can't hardly wait" to become a series regular Seth Green has played a lot of mixed-up kids, but you can say this for him: Each one is mixed up in a completely different way. Take Oz, the blase(with an accent on the e) musician he plays on the WB's Buffy The Vampire Slayer. Green calls him "this incredibly mysterious and unflappable character." He's also a latent werewolf. Then there's Kenny Fisher, a scene-stealing homeboy in the current feature "Can't Hardly Wait." His distinguishing characteristic? "He's a white kid who wishes he was a black kid." Unique behavior is nothing new to the West Philadelphia native: He got a big break starring as the neurotic young Woody Allen character in "Radio Days." Now 24, Green is currently playing a "zombie" (in the upcoming feature "Idle Hands") and preparing to reprise his role as surly Scott Evil in the sequel to "Austin Powers: International Man of Mystery." (He just got the top-secret Mike Myers-penned script, about which he'll only say, "It takes everything that was in the first movie one step further, if not five steps further.") Green's mug has also turned up in guest-star roles on "The Drew Carey Show," "Mad About You" and "Cybil," but now he's happy to be joining Buffy as a full cast member. "I was hesitant to commit to something, since I'm doing features," he admits, "but I think the show's really good." And he's happy to pal around with Alyson Hannigan, who plays his girlfriend, Willow. "We did a movie, 'My Step-mother is an Alien', when we were like 13." But perhaps his quirkiest role was as one of two "stoner kids" found wandering around "an Area 51-type place" in an early episode of "The X-Files." "If you watch," says Green, "you can see David Duchovny and me making stupid faces at each other."