For one day, the center of the fanboy universe will be the Los Angeles Comic Book and Science Fiction Convention, where exhibitors hawk a wide variety of comics, action figures, movies, trading cards and memorabilia. Special guest Billy Dee Williams, who played the space-faring smoothie Lando Calrissian in the "Star Wars" movies, will sign autographs from noon to 2 p.m. Shrine Auditorium Expo Center, 700 W. 32nd St., L.A. 10 a.m. to 5 p.m. Sun. $8 (free for children 5 and younger). (818) 954-8432; http://www.comicbookscifi.com.