Content Warning: This article contains references to the Nazi party, violence, and murder.
Without Oliver Queen (aka the Green Arrow), the Arrowverse wouldn't be the same. The show's Oliver is in many ways different from his more optimistic comic book counterpart, who is often able to joke even when the situation tough. Despite the change of character, Stephen Amell's Oliver became very popular with the fans, partially also due to the fact he changed so much during the course of his show.
However, despite becoming a better person, there were also times when he acted more like the villains and enemies he faced on regular occasions. No matter how many people he helped, it can't erase the fact that Oliver Queen hasn't always acted like a hero.
Cheating On His Partner
Oliver wasn't always an epitome of fidelity or even a good boyfriend. Before he crashed on Lian Yu, he was seen to be seeing both Sara and Laurel at the same time.
Even though he was in love with Laurel and they had been in a committed relationship, as soon as things were getting more serious, Oliver freaked out and cheated on Laurel with her sister. Laurel only found out about this when she discovered Sara was on board The Queen's Gambit. Not only was Laurel taken aback by the betrayal but Oliver was partially responsible for the brief strain between the two sisters.
Being A Nazi Leader
Even during his darkest times, Oliver was never quite as bad as his Earth-X counterpart who was genuinely evil. On this version of Earth, Oliver and Kara were married and they worked side by side as leaders of the Nazi party to control their world and kill everyone who stood against them.
He went as far as to be willing to kill Supergirl in order to transplant her heart into his dying wife. He met his end in the crossover's final episode but not before doing a lot of damage to the world as its leader.
Hurting His Friends
Other than hurting his friends and family psychologically by lying to them, Oliver also sometimes hurts them physically. And he did it just to prove a point or to stop them from doing something he didn't like.
For example, at one point, he shot Ray Harper into a knee with his arrow. He also shot Barry Allen with arrows during Barry's training - despite the fact that Oliver and Barry were already friends by this point.
He Was Killing People
It's true that Oliver's decision to kill people from his father's list in the first season made for a very efficient way (for Oliver, anyway) to stop them for good. At the same time, it made Oliver no different than the people he was fighting. Killing others goes against the moral code for most superheroes, yet Oliver didn't have the same morality.
He only changed his mind after Tommy had sacrificed his life and decided to honor his fallen friend by not killing people anymore. However, Oliver didn't always uphold the rule.
He Doesn't Help His Friends When They Need Him
To be fair to Oliver, a lot of this has to do with the fact how the Arrowverse is organized. Oliver could easily help solve many of the issues Barry faces, for example, yet he would often stay out of them due to personal feelings. He also doesn't seem to be there for his friends when he needs them the most, often putting his own interests above everyone else's.
Oliver Doesn't Trust His Friends And His Team
While this might not seem like a big deal at first, it doesn't exactly paint Oliver in a positive light. Oliver has serious trust issues, which means he doesn't even trust the people he works with - his team.
Even when Oliver sometimes has a point - like when he doesn't trust John's newly found brother Andy - he still could have voiced his objections in a more gentle manner. Oliver also didn't trust his new team - Rene, Curtis, and Dinah and went as far as to spy on them without them knowing - so a lot of unnecessary conflicts erupted between them as a result.
Oliver Doesn't Care About Collateral Damage
Oliver gradually grows more responsible on the show but his behavior still leaves a lot to be desired on more than one occasion. For example, he doesn't care about the people he accidentally hurts with his actions. When he kills his victims in the first season, he pays no mind to whether they have partners or children.
He stabs prison guards who stand against him when he tries to find Ricardo Diaz. And he never bothers to check whether his killed friends - Shado and Yao Fei - have any remaining family who might be interested to know what happened to them.
He Tortured People
Finally, other than killing those who stood in his way, Oliver also sometimes decided to torture his enemies. Again, he usually saw no other option but that doesn't excuse his actions. In Hong Kong, Oliver takes a long time to torture general Shrieve even once it becomes obvious there's no further information the general can give him.
He also at one point starts skinning one of Konstantin Kovar's men alive - simply because once again, the man is unable to provide Oliver with the information he's looking for. That makes Oliver very different from some of his superhero friends and it also makes it dubious whether he deserves to be called a hero in instances such as these.
He Joined The League Of Assassins
Even though Oliver's intentions were noble when he joined the League, he still thought it appropriate to join the League, an evil organization designed to kill people (they have it in their name, after all). However, no one knew this originally, which is what drove a wedge between Oliver and his friends once again, especially him and John.
The main reason for this was that Oliver kidnapped Lyla, put her life in danger this way, and broke John's trust - which is just not something good people do to their friends.