A comedy film based on Meg Cabot's novel about a teenage girl who becomes a princess of Genovia. Starring Anne Hathaway and Julie Andrews, the film was a surprise hit and spawned a sequel. The Princess Diaries (2001) is a heartwarming family comedy starring Anne Hathaway in her breakout role as Mia Thermopolis, an ordinary teenager who discovers she is the heir to the throne of a small European country. As Mia learns about her royal heritage, she must navigate the challenges of becoming a princess while staying true to herself. Directed by Garry Marshall, The Princess Diaries is a fun and uplifting story about transformation, self-discovery, and the power of embracing who you ... The Princess Diaries : Directed by Garry Marshall. With Julie Andrews, Anne Hathaway, Hector Elizondo, Heather Matarazzo. Mia Thermopolis has just found out that she is the heir apparent to the throne of Genovia. With her friends Lilly and Michael Moscovitz in tow, she tries to navigate through the rest of her sixteenth year. A socially awkward but very bright 15-year-old girl being raised by a single mom discovers that she is the princess of a small European country because of the recent death of her long-absent father, who, unknown to her, was the prince of Genovia.