5. Season 5: The Body
This moment was probably the most real any episode of Buffy has ever felt and certainly had a very important effect on the character. Although we had seen Buffy grow up in various ways throughout the series (considering Buffy was only 22 when the show finished, and 20 when her mother died, she was incredibly mature for her age) the moment when Buffy walks in and witnessed her mother has died of natural causes on the couch is truly devastating. It has to be one of the most difficult, yet beautifully directed episodes on television in history. Buffy's mothers death changed her forever. It was a harsh reminder of the reality of life and death. Most of the deaths Buffy had witnessed in the past had been supernatural of some-kind, so witnessing a death that not only did Buffy have zero control over, but that could happen to pretty much anyone at anytime was an important lesson for Buffy and really brought her back down to earth. Her death also forced her to take on the role of mother to Dawn, which was all important considering Buffy would have to protect her at the end of the series from being killed by Glory and even her friends (though in completely understandable circumstances that never actually happen). Not only Buffy, but this episode acts as similar reminders for the rest of the character but particularly Dawn and Anya... and this episode marks perhaps the first true time we have seen Buffy and Tara bond in a significant way ( a friendship that will be important to Buffy in the sixth season).