It depends on whether you ask about characters I liked initially but hated what they ended up like or characters who jumped the shark so badly that they made me dislike them altogether. If it's the former, I can say pretty much everyone in BtVS S7 and AtS S5 was ranging from somewhat annoying to "OMG, get this idiot off my screen now!". Willow, Buffy and Giles in particular resembled the original versions of those characters about as much as the jungle resembles the Arctic wasteland, while Spike literally became the epitome of what he used to mock.
If it's the latter, it's mostly Spike and Buffy. I can't honestly claim I ever loved them (especially Spike) as much as I did love some other characters but I enjoyed them quite a bit. Nowadays, sometimes even my very favourite episodes are overshadowed of thoughts along the lines of "Damn, why didn't you stake him early on, you idiots!" or "Man, Buffy never really learns, does she?". Which is curious, because if I put my objective hat on for a moment, I would say Willow and Giles were just as butchered as Buffy and Spike but this never stops me from enjoying them in S1-4 in the slightest. I never watch Becoming and yell "No, Willow, don't do that spell or else magic!crack awaits you." 🙂
So much word. Willow's entire story becomes all about magic and being a lesbian. I am more than fine with her being a lesbian witch, (heck, I have read tons of fanfiction along those lines and even written some), but not at the cost of losing pretty much all that defined her "Willowness" and made her a fan favourite in the first place. For me personally, the only way to continue adoring her was to treat S6-7 as very bad fanfiction.
Heck, pretty much all of BtVS's problems in the latter seasons were caused by the writers going for "cool" instead of substance, but that's another topic.
If it's the latter, it's mostly Spike and Buffy. I can't honestly claim I ever loved them (especially Spike) as much as I did love some other characters but I enjoyed them quite a bit. Nowadays, sometimes even my very favourite episodes are overshadowed of thoughts along the lines of "Damn, why didn't you stake him early on, you idiots!" or "Man, Buffy never really learns, does she?". Which is curious, because if I put my objective hat on for a moment, I would say Willow and Giles were just as butchered as Buffy and Spike but this never stops me from enjoying them in S1-4 in the slightest. I never watch Becoming and yell "No, Willow, don't do that spell or else magic!crack awaits you." 🙂
So much word. Willow's entire story becomes all about magic and being a lesbian. I am more than fine with her being a lesbian witch, (heck, I have read tons of fanfiction along those lines and even written some), but not at the cost of losing pretty much all that defined her "Willowness" and made her a fan favourite in the first place. For me personally, the only way to continue adoring her was to treat S6-7 as very bad fanfiction.
Heck, pretty much all of BtVS's problems in the latter seasons were caused by the writers going for "cool" instead of substance, but that's another topic.