William Peterson As Gil Grissom – Then

The original head of the team, Gil Grissom was played by William Petersen. For the first eight seasons, Petersen had a consistent character presence in each and every episode, before he left the main cast.

William Petersen – Now

After starring in nearly 200 episodes of the show, Petersen took a break for two years out of the spotlight to focus on his family life. The actor made a return to television when he joined the cast of the period drama Manhattan. Petersen has also worked in theatre since his exit from CSI.

Paul Guilfoyle As Jim Brass – Then

Even though before CSI, Paul Guilfoyle starred in well-known movies such as L.A. Confidential and Amistad, his role as detective Jim Brass is what he will be most remembered for. Guilfoyle played his part amazingly as the captain of the homicide team for a long-running 14 years. However, the show’s creators decided to write him out, after over 300 episodes. However, he did return for the series finale.

Paul Guilfoyle – Now

Since his departure from the show, Guilfoyle has starred in an array of critically acclaimed box office hits. He made an appearance in the sci-fi movie Gravity by Alfonso Cuaron, and a couple years later, the main role of Peter Conley in the crime drama Spotlight, both of which won the Academy Award for Best Picture.

Eric Szmanda As Greg Sanders – Then

Greg Sanders was introduced into the show as a much-needed comedic element to the serious air of the series. But as time passed by, his character became more and more popular as a loved character on the show and it wasn’t long before Szmanda was a regular fixture.

Eric Szmanda – Now

Since the show’s ending, he has kept a low profile in regards to acting. However, he has shown a keen interest in activism and is a strong supporter of the U.S. Campaign For Burma, having traveled to Thailand and seen first-hand the Burmese refugees who flee their country and what they go through on a day-to-day basis.