“I know I’m one of only a few people who feel this way, but don’t @ me to give me hate because I don’t care. It’s nothing against Misha Collins or his portrayal. I just felt that adding this character was a mistake. I guess maybe it might make sense when I explain that I also think the show should have ended with Season 5. The show just rambled on mercilessly from there.”

—atticcrazy

“I don’t think much of Collins’ acting ability, but that’s not even the real issue; he should’ve been killed off at the end of Season 5, plain and simple. The character was utterly superfluous after that point. I still find myself wishing the writer’s strike had never happened. Castiel was a poorly thought out, last-minute invention meant to patch up loose ends when the season got shortened by several episodes. The original plan was for Sam to rescue Dean himself, which would’ve been amazing, with the added bonus of sparing us all a decade-plus of one of the most irritating, overrated side characters in television history.”

—relly

Source: https://www.buzzfeed.com/laurengarafano/tv-characters-ruined-their-shows