I discovered Buffy at the end of middle school, after it had been off the air for several years. It definitely changed my life, in the same way that reading Harry Potter or listening to my favorite band changed my life... Something just clicked and I felt less alone in the world.
BtVS was everything I could ask for in a TV show -- funny, smart, dark, deep, shallow, relateable, ongoing -- and it really filled a gap for me. I love pop culture as much as I love drama and action and magic... This was everything. I realized that there were people out there like me, who created and appreciated the same kind of art that I did, who viewed the world in the same way I did... The show wasn't pretentious, but it wasn't cliche either. It felt so real. And this show lasted for seven seasons, plus a five season spin-off, so many hours of stories that I could enjoy and continue to engage with for so many years of my life. I truly feel that this show is something very special, as there has not been anything like it, before or since it aired.
In a more personal way, season 6 resonates with me so completely as such an honest portrayal of depression, both through Buffy and Willow. I could relate so thoroughly to the characters throughout the whole show but this was the first time I really saw a TV show take it there, go that dark and that deep into pain and heartbreak and loneliness and everything that I felt as a teenager as well. At times I felt no one around me understood me, but the characters somehow did.
I don't know if that sounds super dramatic or what, but yes, it definitely changed my life!