William Petersen as Gil Grissom was the face of CSI: Crime Scene Investigation for several seasons until his exit from the series, and CBS tried to replace Grissom numerous times until the show ended in 2015. The procedural forensics crime drama television series, created by Anthony E. Zuiker, ran for 15 seasons after its premiere in October 2000, and its cultural impact is significant and undeniable. CSI: Crime Scene Investigation was the beginning of a franchise, including multiple spin-offs (CSI: Miami, CSI: NY, CSI: Cyber, and CSI: Las Vegas). But the original show is undoubtedly the franchise at its greatest.
https://screenrant.com/csi-gil-grissom-replacements-lab-director-changed/