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The character of Charlie Dixon was played by Tim Guinee in the original pilot. His scenes were re-shot with Dean Winters before the show aired in early in 2008 and Dean Winters played the character throughout the series.
In 2012, online petitions were set up for the series to be brought back and a 3rd season to be commissioned. The campaign to bring back the series continued even throughout 2015.
Summer Glau got the role of Cameron based partly on the strength of her fight scenes in Serenity (2005). Josh Friedman wrote the character with Glau in mind.
The character "Cameron" is a tribute to James Cameron, who wrote and directed The Terminator (1984) and Terminator 2: Judgment Day (1991).
This series effectively 'retcons' Terminator 3: Rise of the Machines (2003), continuing the Terminator universe from the end of Terminator 2: Judgment Day (1991).
Summer Glau initially did not want to audition for the role of Cameron Phillips, believing she did not look right for the role. However, her mother Mari convinced her to go to the audition and Glau ended up getting the role.