Oliver Queen (Arrowverse)

Early Life
Oliver was born to Robert and Moira Queen and grew up wealthy, privileged, and spoiled. Caring more about his alcohol and womanizing than in running his family's company, the irresponsible playboy at one point got a woman named Samantha pregnant. Rather than force her son to take any responsibility for his actions, his mother Moira gave Samantha a generous check to hush her up and sent her on her way.

Despite these and other character failings though, Oliver did love his parents and sister Thea (who, little did he know at the time was actually his half-sister). One fateful day, he went on a cruise with his father and his then-girlfriend Laurel Lance's sister Sarah (with whom he was cheating on Laurel). Unfortunately for all on board, the ship was destroyed, Sarah believed lost, and Oliver, his father, and another man adrift in a raft. Knowing only one of them would be able to make it, Robert killed the other man and himself, leaving Oliver at the mercy of the island Lian Yu.

Five Years in Hell
For the next five years, Oliver Queen would be locked in a desperate struggle to survive, and steadily went from spoiled, self-entitled playboy and hard-drinking womanizer, to an increasingly brutal, hardened, and ruthless killer. Though routinely going up against various villains and criminals, Oliver himself became increasingly comfortable with murdering and torturing his victims, including a man who was selling his sister drugs, and Matthew Shrieve after the latter killed scores of innocents in China.

By the time of his last year away from home, Oliver willingly joined a criminal group called the Bratva just to get a shot at his target, savagely murdered his enemies with impunity, and even fatally skinned a man alive, an act that was so brutal it even shocked his friend and fellow criminal Anatoli. By this time, Oliver was also actively wearing a green costume provided for him by Talia al Ghul (who herself brought out the worst in Oliver), and so was prepared to one day return to his city and become a vigilante.

Killer Vigilante
Upon returning to Starling City, Oliver as a costumed vigilante wasted no time murdering people who's names were in a book his father had left him of various corrupt officials and businessmen in Starling City. So it was that Oliver as first "The Hood" and then "The Arrow" murdered target after target, criminal after criminal, which put him at odds with the city's law enforcement and prompted concern from those of his allies who were sympathetic to his cause but less his methods (such as John Diggle). Eventually though, Oliver steadily toned down his murderous and bloodthirsty approach, but even after would still occasionally kill his enemies and what's more, he continued to torture many of his victims. When the Flash expressed shock and disapproval at this kind of brutality, Arrow responded with self-righteous indignation, lashing out at the Flash for daring to object to his use of torture to get what he wanted. Not long after this incident, Oliver would compromise his principles yet again by joining the League of Assassins and serving Ra's al Ghul (as well as marrying one of his daughters against her will). Though his time with the League proved short-lived, this would prove yet one more dubious act on Oliver Queen's part.

Over a year later, after murdering Hive leader Damien Darhk in retaliation for his murder of Laurel Lance, Oliver decided that "killing was back on the table", and so once more adopted a murderous approach to crimefighting, until being confronted with the consequences of his past murders in the form of Prometheus, a supervillain who was in fact the son of one of Oliver's previous murder victims, and now eager to pay Oliver back for the vigilante's killing of his father. After being tortured by Prometheus and seeing the consequences of his murderous approach laid bare in front of him, Oliver was once more given reason to question his vicious approach to crime-fighting.

Personality
After three weeks of training under the league, Oliver's original personality (apparently) has been completely extinguished, as he is now loyal only to Ra's al Ghul and the League of Assassins, in terms of his new personality; Al-Sah-Him is stoically cold-hearted, cruel, sadistic, ruthless and immoral, he kidnapped his former Lyla Michaels without any qualms, guilt or remorse.

Al-Sah-Him is (secretly) arrogant, despite this he never underestimate his enemies, is also slow at killing his opponent, implying that he is bloodthirsty, when he saw the person who shot an arrow into his arm, was his half-sister, Thea, he was horrified, revealing that is still trace of his original original personality left; despite this, this does not prevent him from attacking or killing his former friends, allies and half-sister if they get in his way.

Despite these negative traits of his, Al-Sah-Him still has a strong sense of honor.

However, it was later revealed that these new traits of his were nothing more than a façade; as Oliver was secretly taking down Ra's al Ghul and the league from the inside.

Trivia

 * This take on Oliver is significantly darker than any other depiction, given his willingness to not only torture but outright murder scores of enemies, commit pre-meditated murder, and even skin someone alive.
 * The premise of Oliver succeeding Ra's al Ghul and becoming leader of the League of Assassins (and marrying one of his daughters too), is ironically what Ra's al Ghul has long wanted for Batman in most forms of media (a character who Green Arrow is traditionally very similar too).
 * This is the second major live action depiction of Green Arrow, the first also being from a CW TV show (Smallville).
 * In a possible future visited by the Legends, Oliver retired the Green Arrow identity after the loss of his arm and most of his friends, only to come out of retirement in 2046 at the urging of Sara Lance. The premise of a Green Arrow in a dystopian future who is missing an arm is a direct reference to how Green Arrow is portrayed in The Dark Knight Returns.