Bellisario and actress Deborah Pratt, Troian Bellisario's entrance into the entertainment world was inevitable. Born on Oct. 28, 1985 in Los Angeles, Bellisario made her onscreen debut at the age of three opposite Tom Berenger and Daphne Zuniga in "Last Rites" (1988) - a film her father wrote, directed, and produced. The future star was often cast in minor roles on shows her father created, including the sci-fi series "Quantum Leap" (NBC, 1989-1993) and the military drama "JAG" (NBC, 1995-96; CBS, 1997-2005). Two of Bellisario's closest friends growing up were child stars-turned-entrepreneurs Mary-Kate and Ashley Olsen, who cast her in their 1998 film, "Billboard Dad," about twin sisters who attempt to set up their widowed father with a girlfriend by painting a giant advertisement situated above L.A.'s Sunset Boulevard. Bellisario also acted opposite her stepbrother Sean Murray on the crime drama series and "JAG" spin-off, "NCIS: Naval Criminal Investigative Service" (CBS, 2003- ). On the show she played the onscreen sister of Murray's character, a computer forensics specialist and a special agent for an elite team that investigates criminal activity in the U.S. Navy and Marine Corps.
In 2010, Bellisario landed a starring role on the ABC Family mystery drama, "Pretty Little Liars." The program was based on author Sara Shepard's 2006 novel series of the same name, which chronicled a group of friends whose clique falls apart after their queen bee inexplicably disappears and an anonymous foe threatens to reveal their darkest secrets. Bellisario played Spencer Hastings, the overachieving and competitive member of the group who develops a forbidden crush on her sister's fiancé. Described as a young adult version of "Desperate Housewives" (ABC, 2004- ), "Liars" tackled such controversial issues as body image and homophobia, and was well-received by TV viewers and critics. The series launched Bellisario and her co-stars Lucy Hale, Ashley Benson and Shay Mitchell into the upper ranks of young Hollywood, gracing the covers of magazines and attending major award shows. That same year, Bellisario joined the ensemble cast of the comedy feature "Peep World," which included Michael C. Hall, Sarah Silverman and Taraji P. Henson on the talent roster.