"Supernatural declined after season 5 in several ways, but the most significant factor was likely the change in showrunners. Eric Kripke's departure marked the end of the show's strong horror influence."
Riverdale (2017-2023)
"The most significant and disastrous change in Riverdale was the introduction of supernatural elements, which completely altered the genre that the show's audience had come to expect."
Heroes (2006-2010)
"Heroes introduced a brilliant new premise to TV, but poorly written characters and unresolved subplots soon overshadowed it. The 2007 WGA strike disrupted season 2, and the show never managed to recapture the magic of season 1."
Game Of Thrones (2011-2019)
"Game of Thrones' widely criticized final season earned its reputation through nonsensical plot twists and ruined character arcs."
Lost (2004-2010)
Lost turn out to be a mystery that could never be solved, which is why it declined over time.
Glee (2009-2015)
The over-the-top drama becomes irritating, casting doubt on the quality of past seasons. Glee then stretches believability by having most of the characters end up in New York City after high school graduation
The Walking Dead (2010-2022)
The Walking Dead eventually falls into a repetitive cycle of searching for safety, finding a temporary sanctuary, encountering a new human enemy who demonstrates that humans are the real monsters, and then having the sanctuary destroyed, forcing the main group to flee once more.