Arrow's Main Villains Ranked From Worst To Best

"What? There are villains more evil than the one that killed Ollie?", you might be saying. And the answer, of course, is yes - for as the best supervillains always know, why kill your enemy when you can make him suffer?

Among Oliver Queen's few, few friends on the purgatorial Lian Yu was Slade Wilson, an Australian Intelligence agent tasked with rescuing the Chinese prisoner, Yao Fei, from the island. Though this mission fails, Slade remains trapped in Purgatory, and, along with Yao Fei's daughter, Shado, trains Oliver in combat and proficiency with a bow.

Slade grows secretly attached to Shado, and when she is suddenly killed by the villainous Dr. Ivo, he blames Oliver for her death and vows revenge. Thanks to the experimental drug, 'mirakuru', which both enhances his strength and alters his brain chemistry, Slade blows this vendetta WAY out of proportion, spending years following his time on Lian Yu plotting how to make Oliver suffer as he has. (Probably didn't help either that Oliver stabbed his eye out in their confrontation.)

Their reunion in Starling City is as messy as you'd expect, resulting in Slade, now known as Deathstroke, murdering Oliver's mother, Moira Queen. A later scuffle between Team Arrow and Deathstroke's mirakuru-enhanced soldiers sees Slade incarcerated in a purpose built prison cell on Lian Yu.

Though this ends the one-eyed psycho's reign in the series, Deathstroke does make a handful of appearances further down the line, reminding us that he's still out there, no doubt waiting to strike again.