Remember "Dark Shadows," the gothic soap popular in the mid-'60s? Fans can enjoy their own flashback this weekend at the Dark Shadows Festival at the Los Angeles Airport Marriott, Friday through Sunday. Jonathan Frid (who played the vampire), Kathryn Leigh Scott, Laura Parker, John Karlen, other actors, writers and crew members are scheduled to appear. Hours are Friday, 6 p.m.-2 a.m; Saturday, 9 a.m.-2 a.m.; Sunday, 9 a.m.-8 p.m. An autograph session begins Sunday at 6. A three-day festival pass is $20. Information: (213) 466-0084.