CSI originally starred William Petersen and Marg Helgenberger alongside an ensemble including George Eads, Gary Dourdan, and Paul Guilfoyle. Jorja Fox joined the cast in episode two of the first season, whilst Eric Szmanda and Robert David Hall recurred throughout the first two seasons of the show before being promoted to regular status starting with the third. Louise Lombard, who first appeared in season five, joined the cast starting with season seven. The first major cast overhaul came with the show's eighth and ninth seasons. Lombard departed the cast in the first episode of season eight, whilst Fox departed in episode seven of the same season. Wallace Langham joined the main cast following Lombard's departure, having recurred since the third season. Fox would return for guest appearances during the ninth season in order to facilitate the departures of both Gary Dourdan and William Petersen, who were replaced by Lauren Lee Smith and Laurence Fishburne, respectively. Smith departed the cast at the end of her first year, and was replaced by a returning Jorja Fox, who featured in a recurring capacity. Liz Vassey and David Berman, who had recurred from season six, and season one, respectively, also joined the cast starting with season ten. Like Smith, Vassey departed the cast after a single season, and was replaced by Fox, who rejoined the main cast. William Petersen would appear in voice clips sporadically over the next three seasons. Fishburne departed the main cast at the end of season eleven, a season that featured guest appearances by Elisabeth Harnois and Louise Lombard, and was replaced by Ted Danson. Danson made his main cast debut alongside Elisabeth Harnois at the start of the twelfth season. Series lead Marg Helgenberger departed the main cast in the twelfth episode of season twelve and was replaced by . Season thirteen saw Jon Wellner join the main cast after eight years a guest star. Helgenberger returned for a single episode in season fourteen, while Paul Guilfoyle departed at the end of the same year, followed by Elisabeth Shue and George Eads at the end of the fifteenth season. The show's finale, a two-hour film, featured the return of Helgenberger, Petersen, and Guilfoyle. The series finale marked their final appearances, as well as the final appearances of Fox, Szmanda, Hall, Langham, Berman, Harnois, and Wellner. Ted Danson went on to reprise his role of Russell during season two of Cyber.
