Anne Hathaway played the character Mia Thermopolis.
Anne Hathaway . Hathaway went on to become a widely praised `` role model for children '' for her roles in Nicholas Nickleby ( 2002 ) , Ella Enchanted ( 2004 ) , The Princess Diaries 2 : Royal Engagement ( 2004 ) , and Hoodwinked ! The Princess Diaries (film) . It stars Anne Hathaway ( in her film debut ) as Mia Thermopolis , a teenager who discovers that she is the heir to the throne of the fictional Kingdom of Genovia , ruled by her grandmother Queen Dowager Clarisse Renaldi ( Julie Andrews ) .