Jason Priestley as Brandon Walsh
Fun fact: In his 2014 autobiography, Jason Priestley: A Memoir, Priestley admitted that he regretted leaving the series at the beginning of the ninth season, saying he wished he had stayed on through the entire series run. Hel also felt that his decision to leave hurt his personal relationship with the series co-creator and producer, Aaron Spelling.
Shannen Doherty as Brenda Walsh
Fun fact: Doherty was notoriously difficult to work with. According to Jennie Garth, tensions got so bad that they almost got into a physical fight after Doherty pulled Garth's skirt down during a take in order to have her break character. Garth then turned to Doherty and said, "Come on, bitch! We're talking this outside!" but the fight was stopped by Jason Priestley and Luke Perry before any punches were thrown.
Ian Ziering as Steve Sanders
Fun fact: Ziering also did voice over work during almost the entire run of the series. He lent his voice to cartoons such as Biker Mice From Mars, The Mighty Ducks, Batman Beyond, and Godzilla.
Tori Spelling as Donna Martin
Fun fact: Spelling -- under the alias Tori Mitchell -- originally auditioned for the role of Kelly Taylor. She used the alias so she wouldn't be recognized by casting as Aaron Spelling's daughter.
Brian Austin Green as David Silver
Gabrielle Carteris as Andrea Zuckerman
Fun fact: At age 29, Carteris was the oldest cast member to be portraying a teenager. In 2011, she told Access Hollywood that she sort of lied about her age, just saying she was "over 21" when being cast.
Carol Potter as Cindy Walsh
Fun fact: Potter, who was a series regular for five seasons, decided to pursue marriage and family therapy after her contract was not renewed for the show -- though she did guest star several times after the fifth season. She is now a licensed therapist practicing in Los Angeles.
James Eckhouse as Jim Walsh
Fun fact: Eckhouse, who was 35 years old when the series started, was only 14 years older than Jason Priestley, who was playing his 16-year-old son.
Jennie Garth as Kelly Taylor
Fun fact: Before being cast as Kelly, Garth co-starred with Jason Priestley on the The Mickey Mouse Club serial, "Teen Angel." She also auditioned for the role of Kelly Kapowski on Saved by the Bell; the role of course went to Tiffani Thiessen, who would later join 90210 as Valerie Malone.
Luke Perry as Dylan McKay
Fun fact: Perry originally auditioned for the role of Steve Sanders, and while he didn't get the role, he did make an impression on the producers who later cast him as Dylan. Also the role was created for what supposed to be a two-story arc, but Aaron Spelling liked Perry and the character of Dylan so much that he made him a series regular.