By DICK KLEINER HOLLYWOOD — (NEA) It isn’t often you get a chance to meet a black vampire Es pecially one hanging around a mortuary. But there he was, in the per son of William Marshall, the distinguished actor who has played most of the classics and is now starring in “Blacula.” This is the world’s first black horror movie. I'm not sure if this is a step forward or backwards in the civil rights movement, this idea of the black people having their own horror film. However, it’s certainly a sign of the times it’s equality, of sorts, and being equal means you have to take all things, including hor ror movies, in stride. So there was William Mar shall and I’m happy to say that he took his fangs off when the lunch break came. The mov ie is being made by American International, which specializes in horror movies and it’s typical ASP material. It’s full of pretty girls and morsels in such as biting on the neck and drinking blood. They were shooting in a real mortuary — the whole film is being shot on location around town — and the cast was warn ed not to open any doors. “I'm not about to open any of the caskets lying around here,”’ said Denise Nicholas, the beauty from Room 222. “Who knows what's inside?” Marshall, playing a black man who goes to Transylvania and becomes Dracula’s protege, says he’s been getting a strong reaction when he tells people about the film. “It’s stronger,” he says, “than when I played Shake speare or the Greek classics or even when I played me in ‘Green Pastures.’ The idea of eternal life seems to thrill the public. The first day of shooting, I met a girl who said, ‘Oh, you’re the vampire — I've always wanted to be a vam pire!” Marshall says he plans, in two or three years, to quit the business and move away, to Africa (Guinea or Tanzania) or the West Indies. “I want to get away from the smog,” he says, “and I want to teach, I'm teaching now, at San Fernando State, and I just enrolled there as a freshman to get some teach ing credits so I can be ac credited as a teacher when I go” Denise Nicols said that things look good for Room 222 for another season. She’s happy