SPOILERS for Arrow Season 5 Episode 17 Kapiushon.
So in the last episode of Arrow, Oliver admitted he enjoyed killing people so I decided to go through the show to see how many people Oliver has killed (That we know of).
All of these kills are the known kills from Episode 17 Kapiushon.
The number I came up with in the end was 165 people, but I didn't include how many people died in the missile strike of the Season 1 Finale.
In the first 4 years of the flashbacks Oliver only people because he was forced to due to survival or orders. In the present day of Season's 2, 3 and 4 Oliver only killed people because there was no other way.
The Only years Oliver ever murdered people out of ruthlessness is during Season 1 Present day and the Flashbacks and Present day of Season 5.
In the Season 5 flashbacks, so far Oliver has killed 50 people but 2 of these kills were neccessary (Fighting Ring and Bratva Initiation). So this puts his cold blooded kills at 58 for this year (So far).
In Season 1 Oliver killed a total of 65 people by my count. 8 of these kills were justified because Oliver was either protecting himself, his friends or his secret. So that puts cold blooded kills at 57.
In Season 5 Oliver has currently killed a total of 7 people. None of these are justified.
So in the last 10 years Oliver has murdered 165 people and only 53 of these kills are justified.