8 Unforgivable Mistakes Arrow Made (From Which It Never Recovered)

Remember how Malcolm Merlyn spent over a decade attempting to exact revenge on the area of Starling City in which his wife was killed? What about how Slade Wilson meticulously plotted the downfall of Oliver Queen? Two exceptionally well-crafted villains that complemented the gritty tone of the show and ultimately bettered the hero's already phenomenal journey. Unfortunately they set a bar so high that the show would rarely ever reach again.

Following Slade's night of terror, the writers introduced the rather dull Ra's Al Ghul who, save for his Batman-centric comic arc, didn't have anything to offer and attempted to talk Oliver into becoming his successor - even throwing a tantrum when he wouldn't accept the honour. This was all followed by the insufferable Damien Darhk, who was effectively a walking magician that spouted corny one-liners and - oh yeah - wanted to destroy the world in a nuclear fire. (Because no evil supervillain has ever wanted to do that before, right?)

Though the writers corrected their course with the outstanding Prometheus, the standard would slip again with Cayden James. It would rise once more for sadistic street thug Ricardo Diaz before declining again for the highly-underdeveloped Emiko Adachi.

Had the show managed to maintain a strong villain in Seasons 3 and 4, perhaps the writing never would have slipped.