I love almost all the characters on the original CSI. They all have great personalities and usually have the best intentions.
Gil Grissom: The man who knows more things about bugs, forensics, and other random information than he does about human beings. He is the Sherlock of his job and the teacher. He taught everyone on the show how to be a great CSI. They all look up to him and he eventually falls to the human emotion of love when he opens himself up to Sarah. They make a great couple because both are socially inept but manage to understand one another. I was sad when he left, but am happy knowing that he is happy.
Catherine Willows: The former stripper who learns that her dad is a millionaire who owns casinos. She is tough, no nonsense type woman and managed to get respect despite her former job. She takes over when Grissom leaves and keeps everyone inline. A lot of things she says are really funny and I marvel at how the writers never cross the line from strong to bitchy with her. She is awesome!
Warrick Brown: He was a gambler who ran bets for Judges and took a part in Holly Gribbs death during the first episode. He turned his life around and looked to Grissom as a father. He and Nick appeared to be best friends and competitors. It was heartbreaking when he died at the end of season 8. He got mixed up on the wrong side of and organized crime investigation. Grissom gave a tear jerking eulogy and it is clear that it hit everyone hard.
Nick Stokes: Nick started off as a young CSI wanting to impress Grissom. He eventually garnered enough skill and respect when Grissom gave him the letter of recommendation over Sarah. He cares about the victims which gets him into trouble sometimes but it shows that he has a big heart. He gets promoted to assistant supervisor at the beginning of Season 10 which is well earned and gives him even more respect.
Sarah Sidle: Sarah is an intense worker who has almost nothing outside her job. She works constantly and strives for perfection. She opens up her heart to have it broken in season 3. When she lets her emotions go she really lets them go. She has a great friendship with Greg that I always enjoy watching. Her and Grissom are great together romantically and eventually all the emotions just burst through after being kidnapped and it is so much that she has to leave Vegas. She comes back thankfully in season 1o due to the lack of Riley and is much more stable.
Greg Sanders: Originally the DNA tech, Greg has possibly grown the most throughout the series. He goes from collecting porn magazines to being and actual CSI level 3. He is smart, young, and funny. He doesn’t get the most respect but has a good working relationship with everyone. He offers a different point of view coming from an upper middle class family and a protective mother. Basically he is just awesome!
Dr. Al Robbins: Doc Robbins is a snarky, old, brilliant doctor who takes pictures of the famous people that come across his autopsy table. He has great relationships with Grissom, Langston, and David. He also has prosthetic legs and claims that he is never going to retire.
David Hodges: The suck-up trace technician. He is in love with Wendy Simms and goes into a deep depression when she leaves. He respects Grissom a lot even though Grissom seems to be unable to stand him. The CSIs see him as a nuisance but respect his ability in the lab.
Dr. Ray Langston: Ray came after Grissom left as a former pathologist who let an Angel of Death slip by him. He is obsessed with serial killer Nate Haskell and this ultimately leads to his demise. He is extremely smart and controlling and pretty much does what he wants.
Riley Adams: Arrives after Warrick’s death and has a spunky attitude. She is forceful and like Catherine doesn’t take crap. She leaves at the beginning of season 10 and leaves a nasty note making her likeness level drop drastically at the end of her run.
Captain Jim Brass: Is a police detective who has a twisted sense of humor. He is a tough guy with the criminals and not very personal. He seems to only have a real relationship with Grissom and has an estranged “daughter”. All and all, he is hilarious.
Conrad Ecklie: the douche bag day time supervisor who moved up the ranks and became the under sheriff. In the later seasons he became much more likeable. He let Grissom handle Warrick’s death and is able to actually work with the grave shift team.
There are lots of other lab techs with great personalities like Mandy, Archie, Henry, and Bobby too.