Carol Peletier - The Walking Dead
Through seven seasons, Carol has transformed from helpless housewife to badass zombie slayer in her own right. Arguably one of the most beloved characters on The Walking Dead, it's difficult to imagine the series without Melissa McBride. The original plan was to have Carol killed off early in season three, but a last minute decision caused the writers to nix the idea and giving T-Dog the ax instead.
Spike - Buffy the Vampire Slayer
This villain turned fan favorite was meant to be on the wrong end of stake in season two. Lucky for us, series creator Joss Wheden made the wise decision to keep Spike around.
Andy Dwyer - Parks and Recreation
This entry deviates from this list a bit since this particular character wasn't going to be killed off, but simply written out. Chris Pratt's character, Andy, was originally intended to have a limited run on the show as Anne's boyfriend. Much to the delight of fans, Andy stayed around.
Nicholas Brody - Homeland
Nicholas' failed assassination of the vice president wasn't originally intended to fail. Executive producer Alex Gansa explained that they felt there was more story to tell with the character, so they decided to keep him alive.
Carol Hathaway - ER
Originally, Nurse Hathaway was not supposed to survive her suicide attempt in the pilot. Fortunately, that scene didn't test well with audiences and the producers brought the character back. Just think, we could have easily missed out on the relationship between her and George Clooney's, Dr. Ross. And without Carol Hathaway, would we have ever had The Good Wife?
Boyd Crowder - Justified
In the short story in which the series is based, Boyd Crowder is killed during a showdown with U.S. Marshal Raylan Givens. This was meant to take place during the FX series' pilot, but the test audiences were intrigued by the character and were eager to learn more about him. The rest is history.