 Smallville is an American television series developed by writer / producers Alfred Gough and Miles Millar , and was initially broadcast by The WB . After its fifth season , the WB and UPN merged to form The CW , which was the second broadcaster for the show in the United States . The series features a regular cast of characters , which began with eight main characters in its first season . Since then , characters from that first season have left the series , with new main characters having been both written in and out of the series . In addition , Smallville features guest stars each week , as well as recurring guests that take part in mini story arcs that span a portion of a season . Occasionally , the recurring guest storylines will span multiple seasons . 
