9. He Lost A Swordfight To Green Arrow
When Ra's al Ghul was announced to be part of Arrow's third season, a lot of fans were worried about actor Matt Noble's ability to pull off the iconic character.
Those fears seemed to be put to rest though in the episode The Climb. Oliver challenged Ra's to a duel to the death, only to be destroyed by the master assassin. Despite being unarmed, Ra's was easily able to disarm Oliver before running him through with his own sword and pushing him off the side of a cliff.
It was a genuine shock and a big highlight for had generally been one of the show's weaker seasons. It's a shame that when they fought again it was so underwhelming.
Ra's and Oliver fought again in the season finale. However, this time Ra's fell victim to the one weakness of all Arrowverse villains, lazy writing. When it came down to a fight that the show's protagonist needed to win, Ra's conveniently just stopped being a better sword-fighter than Oliver and ended up stabbed to death by an opponent that he could pretty much beat in his sleep before.
It was an anticlimactic end to a pretty anticlimatic season. Still, at least it was better than Season 4.