In the fourth entry in the film series, 18-year-old Marnie Piper (Sara Paxton) attends Halloweentown's Witch University, where she tangles with three wicked classmates and uncovers a sinister conspiracy to control her magic for evil purposes. Dylan Piper: J. Paul Zimmerman. Gwen Piper: Judith Hoag. Aggie: Debbie Reynolds. Ethan Dalloway: Lucas Grabeel. Directed by David Jackson.