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Anne Hathaway made her big-screen debut in The Princess Diaries, playing regular girl-turned-royal Mia Thermopolis with just one credit to her name. The future star earned her first gig in 1999, playing Meghan Green in Fox's short-lived Get Real TV show (pictured above).
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When Julie Andrews signed on to play Queen Clarisse Renaldi, she already had decades in the business and an Oscar behind her. The Sound of Music star landed her first projects in the late '40s and early '50s, including an appearance in a 1956 episode of Ford Star Jubilee, in which she played Lise (pictured above).
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Heather Matarazzo joined The Princess Diaries as Lilly Moscovitz, Mia's best friend. The actress made her debut about a decade prior, picking up early roles in The Adventures of Pete & Pete and Welcome to the Dollhouse (pictured above).
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Hector Elizondo added to his jam-packed résumé with The Princess Diaries, playing Joe, Queen Clarisse's head of security. The actor, who earned his first credits in the '60s, hit the small screen in 1980, playing Det. Sgt. Dan 'Bean' Delgado in Freebie And The Bean.
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After dropping three studio albums and lending her voice to Dr. Doolittle 2, Mandy Moore hit the big screen in The Princess Diaries as Lana Thomas, the leader of the cool girls clique. Moore saw success with her singing career, releasing hit singles like "Candy" and "I Wanna Be With You."
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Caroline Goodall found her spot in The Princess Diaries as Mia's mom, Helen Thermopolis. The star kicked off her acting career in the '80s, landing an early role as Moira Banning in Hook (pictured above).
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The Princess Diaries found its indie dreamboat Michael Moscovitz in Rooney frontman Robert Schwartzman. The son of actress Talia Coppola and producer Jack Schwartzman, the musician was walking red carpets as a young boy, pictured above at the Producers Guild Golden Laurel Awards in March 1993.
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Erik Von Detten
Teen heartthrob Erik von Detten signed on to play Josh Bryant in The Princess Diaries, a popular student who shows a sudden interest in Mia. The star made his on-screen debut years prior, appearing as a child actor in Days of Our Lives in 1993.
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Sean O’Bryan played Patrick O'Connell in The Princess Diaries, a teacher at Mia's school who becomes involved with her mother. O'Bryan rose to fame in the '90s, appearing in a handful of episodes of Pig Sty as Iowa.
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Years before she became Grey's Anatomy's Dr. Cristina Yang, Sandra Oh played Vice Principal Gupta, an administrator at Mia's school, in The Princess Diaries. The future star picked up early roles in the late '80s and early '90s, first hitting the big screen in 1994's Double Happiness.
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Two years after he starred in 10 Things I Hate About You as Walter Stratford, Larry Miller popped up in The Princess Diaries as Paolo, a hairdresser brought in to give Mia a makeover. The comedian got his start in the '80s, making an appearance on The Tonight Show starring Johnny Carson (pictured above).