5. Supernatural
Premiering in 2005, Supernatural quickly became one of the most watched television shows on the air. Featuring two attractive brothers as they hunt down demons, malevolent spirits and other paranormal monstrosities, the series has gained a massive cult following and, let's face it, the show was damn good. However, the emphasis is very much on 'was' while there have been a few decent episodes in each season, the fifth marked the end of what made Supernatural worth watching. Supernatural is a perfect example of a show that has run its course by using the same plot formula over and over again. It has also suffered from bad writing as each overall plot since season six and has become more and more ridiculous. Eve the mother of all supernatural creatures? Leviathans corporate, people eating, Biblical monsters that take on human shape? An angel attempting to become the new God? Speaking of angels, it was their introduction to the series that marked a decrease in quality namely around the time that they became plot-driven characters. The more recent seasons have also lacked decent standalone episodes focusing on paranormal investigations and are replaced by corny attempts at humor. Other mistakes that have hurt the series include the reintroduction of demon Meg, keeping Bobby around for as long as they did, revamping the Trickster as archangel Gabriel, and pretty much everything to do with Castiel. The Winchester brothers have gone way too far to give up their demon-hunting careers to live normal lives. Our suggestion kill them and let them stay dead. It doesn't have to mean the darkness has to win, but the boys have got to go. If the series was ended with the fourth or fifth season the brothers could possibly have had the chance to complete their work and settle down but what's done is done.