No, Robert Patrick was not in the TV series Prison Break. It was Robert Patrick Stern who appeared as an inmate in the pilot episode of "Prison Break" in 2005. He is also known for his work on The Rake, Dead 7 (2016) and The Stylist (2016).
Robert Patrick on the other hand, starred in various direct-to-video television movies, and had a short appearance in Die Hard 2 (1990). His breakthrough role came as T-1000 in James Cameron's blockbuster Terminator 2: Judgment Day (1991). After that, he landed roles in various feature films such as Last Action Hero (1993), Fire in the Sky (1993), and Striptease (1996).
Patrick's performance in "Fire in the Sky" caught the attention of Chris Carter, creator of the television series The X-Files (1993). After David Duchovny distanced himself from the series during its seventh season, he was cast as FBI Agent John Doggett.
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