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'Beverly Hills 90210'
Abruptly departed: Shannen Doherty
Played: Brenda Walsh
Lasted: Four years (1990-94)
Why she left: Doherty was reportedly as difficult on the set as she was off the set. When alleged clashes ensued between Doherty and Jennie Garth, she and the producers had a sit-down and all parties agreed that Doherty should leave.
How it went down on air: After her first year at college, Brenda moved to London to pursue her acting career at the Royal Academy for Dramatic Arts and was never heard from again.