2. Denise Crosby - Star Trek: The Next Generation
The exit of Tasha Yar from Star Trek: The Next Generation, shocking as it was at the time, kind of gave us the vibe that it wasn't exactly an amicable departure. Denise Crosby, who along with Gates McFadden and Marina Sirtis were very vocal about the sexist undertones that dominated the first season of the show, decided to part ways with the series three quarters of the way into the first season. She could have died in a firefight (she was the chief of security after all), she could have died in a shuttle crash, she could have even died off-screen. All thesewould have been better than what she got, and that was that a seriously ticked off alien covered in Metamucil and black printer ink crushed her head in for fun, leading to one of the most heart-breaking and head-scratching moments in the show's nearly 50 year run. Not long after that, Gates McFadden was fired from the show for the same reasons leading to unrest among the fans and even the cast. When the late great Michael Piller took the reins for the infamous Maurice Hurley, Gates was asked to return as a series regular and Denise was brought back in a guest capacity whereby the timeline is slightly altered by having Tasha die as a Romulan prisoner of war in the aftermath of "Yesterday's Enterprise," but not before giving birth to the main Romulan baddie of TNG, Sela. In spite of this, sge still very much remembers the goo alien crushing in her head, so while the events of that first season episode still happened Tasha was given a much better way out upon her first return as a guest.