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Before she took on the role of clique leader Spencer Hastings, Troian Bellisario built up her résumé over the course of a decade. The actress started her on-screen career as a child star, picking up bit parts in Last Rites (1988) and Billboard Dad (1998), and appearing in one 1990 episode of NBC's Quantum Leap (shown above).
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Before she was a resident of Rosewood, Penn. as Pretty Little Liars' Hanna Marin, Ashley Benson played a little girl living in California in one 2002 episode of The West Wing. Earning one of her very first on-screen credits, Benson played an unnamed girl who is shown supporting the congressional campaign of Hornton Wilde in Orange County.
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Lucy Hale may have risen to fame as the offbeat Aria Montgomery on PLL, but she spent her teen years filling up her filmography with sporadic small-screen appearances. Hale earned early credits for one-off roles in Drake & Josh and The O.C., and played Becca Sommers in NBC's failed Bionic Woman series in 2007 (pictured above).
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Before joining PLL as teacher Ezra Fitz, Ian Harding earned credits for unnamed roles in movies like Adventureland and Love and Other Drugs, and played Jamie Hunter in six episodes of the web series Hollywood is Like High School with Money (shown above).
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Laura Leighton plays Hannah's mother Laura Leighton on Pretty Little Liars, a role she came into after two decades in the industry. The actress picked up one of her very first roles as Sydney Andrews on Melrose Place, appearing on the soap from 1993 to 1997 (shown above).
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Shay Mitchell made her Pretty Little Liars debut as Emily Fields, an athletic member of the clique, just two years into her on-screen career. Before landing the gig, Mitchell played an unnamed model in one 2009 episode of Degrassi: The Next Generation (shown above).
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Sasha Pieterse appears in Pretty Little Liars as the popular queen of the school, Alison DiLaurentis. Pieterse picked up her first credited on-screen role in 2002, playing Buffy Davis in The WB's short-lived Family Affair revival (shown above).
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PLL found its Mona Vanderwaal in Janel Parrish, a Hawaii-born actress and singer, who made her on-screen debut in the late '90s. The star landed her first credited role on Baywatch, playing Hina in two episodes (shown above) once the show made the move to the island.
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Tyler Blackburn joined PLL as bad boy Caleb Rivers. Before taking on the gig, Blackburn filled his résumé with small-screen roles, debuting as Nathan in two 2005 episodes of Unfabulous (shown above).
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Holly Marie Combs
Holly Marie Combs appears in Pretty Little Liars as Ella Montgomery, the mother to Hale's Aria. She has decades of work to her name, including an early role as Jenny in 1989's Born on the Fourth of July (pictured above).
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Keegan Allen found his spot on PLL as Toby Cavanaugh, the step-brother to Tammin Sursok's character of Jenna Marshall. Allen picked up one of his first on-screen credits the same year he made his debut as Toby, playing an unnamed male model in one 2010 episode of Big Time Rush (shown above).
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Years before he played Byron Montgomery, the father to Aria, on PLL, Chad Lowe was building his résumé with TV and film roles. He landed one of his very first projects in 1984, starring opposite Charlie Sheen in the TV movie Silence of the Heart.