HOLLYWOOD — Seth Green has signed to star opposite Sarah Michelle Gellar, Freddie Prinze Jr., Matthew Lillard and Linda Cardellini in Warner Bros.’ “Scooby-Doo” sequel for helmer Raja Gosnell.Green will play Patrick, a mysterious museum curator at the Coolsonian Criminology Museum. Pic, penned by James Gunn, is being produced by Charles Roven and Richard Suckle of Mosaic Media. Sequel begins shooting April 14 in Vancouver and will be released Stateside March 26, 2004. Green, repped by UTA and Koopman Management, will next star in Paramount’s upcoming “The Italian Job,” opposite Mark Wahlberg, Charlize Theron and Edward Norton. He also toplines Killer Films’ “Party Monster” with Macaulay Culkin.