Not even counting the shipwreck, Oliver's castaway ordeal was nightmarish before he ever reached the island. Namely on the life raft, Oliver watching his father murder another man and then kill himself. Oliver spends countless days floating aimlessly a few feet from his father's sun-bloated, near-headless corpse as the water slowly runs out. He finally reaches the safety of the island's dry land, only to watch seagulls feasting on his father's rotting body. Even if Oliver had been rescued the day after he reached the island, he already experienced enough horror to justify spending the rest of his life gibbering in a padded cell.
The effects of Vertigo when put in the jugular. It puts the brain's pain receptors on overdrive, causing a crippling amount of psychosomatic pain that can last for days before the person's heart gives out.
The Undertaking: A bunch of rich, powerful people decide to "fix" their city by making the poor side of town the worst it can be, probably to justify whatever renovation efforts they care to make. In the process they do things like corrupt the legal system, stop gentrification projects and shut down free clinics and other social support organizations. If you're one of the poor people harmed by this project, oh well...
Turns out they were actually trying to save the city, but the Undertaking is now bringing down the Glades with an earthquake machine!
Malcolm's Suddenly SHOUTING! moment right before the Undertaking takes place, which somehow crosses this with Tear Jerker. It's both completely tragic and shows how completely crazy he's become since his wife's death.
Tommy: So you kill them all-? Malcolm:YES! THEY DESERVE TO DIE!ALL OF THEM!! The way she died!
Deadshot. Even if you survive with just a graze, you'll be dead from the curare poison he laces his bullets. And good luck using bulletproof glass. He'll just shatter it and fire another round immediately after.
The Island as a whole. With WW2 mines laying about, armed mercs who'll grab and attack anyone they see and torture for info they may not even have, the fact that both a crashed plane and two boats have ended up there like the Bemuda Triangle, and the questionable implication of what, exactly, the hell are they even doing there. The realization that it was able to transform a shallow party boy into a hardened killer in mere years will make you think twice about any trip overseas.
The Doll Maker. The first victim we see of him is treated in a more gruesome, CSI kind of way and when Quentin sees the body, he's visibly disturbed. The killer himself is creepy as hell, and takes disturbing pleasure in drowning his victims and turning them into his dolls.
"Broken Dolls" also gives us Slade getting hit by one of the pirates' mortars and set on fire. It is later shown that the damage caused an extremely nasty burn on the entire right side of his head.
In "Crucible" Sara Lance says, "No woman should ever suffer at the hands of men." Some fans have pointed out that this may be an oblique reference to being raped at some point during the six years she was missing. At any rate having spent the time on Amazo, Lian Yu, or in the League of Assassins she's likely to have been through some terrible things - equal to or greater than Oliver.
League of Assassins has her, when she's first found by the Amazo, being dragged out in front of several men in nothing but a shirt and her underwear, with the obvious implication they were planning to gang-rape her. Dr. Ivo saves her from it, but she's left terrified and shaken, so much so she flinches when he locks the door (not to stop her leaving, mind, to stop the others coming in).
Speaking of such, the League of Assassins themselves; highly trained assassins capable of catching arrows without flinching, almost immune to pain. Their ranks are large and they can come in, take out their target, then leave without ever being seen, with only rumours of their existence in the far east, despite them operating throughout the world. They transform people with no combat skill prior into ruthlessly efficient killers, in less than two years time. And given that the show is now embracing super powers, its possible Ra's Al Ghul may in fact keep his immortality here, making him all the more scary.
"The Scientist" confirms that yes, Professor Zoom does exist in this universe, and he's already jumping around Barry Allen's timeline.
From "Three Ghosts" Oliver's hallucination of Slade attacking him, especially when we learn the hallucinations are purely psychological. He gets beat up, tables are tossed, and thrown into a glass case, and all the time we know that he's doing it to himself.
Plus, this scene is highly reminiscent of Robin's hallucination of Slade (also thought to be dead) in Teen Titans, and it was mighty effective then as well.
The Count. He was creepy enough to begin with, but once the Vertigo takes effect, he's left completely insane and terrifying on a whole other level. Even worse, he's played by Lincoln!
What happened to Sebastian Blood's parents: he killed his father and framed his mother for it, putting her in a nuthouse. When Laurel sees his mother, she seems to be in a Madness Mantra. When Laurel mentions Sebastian's name, it snaps her out. You know something's messed up when your own mother calls you the Devil.
In "Blind Spot", the mind games that Blood plays with the already fragile Laurel are terrifying, to the point that she can no longer trust herself.
From "Tremors", the effect that Mirakuru has on its victims. Roy goes to see Thea and begs her to leave the city. She asks for a reason, and within ten seconds he gets frustrated and starts unconsciously crushing her arm. He realizes what he's doing and stops before she's hurt, but it's still very disturbing both to Roy and the audience. In the flashbacks, Slade nearly blows up their only way off the island in his desperate mission to avenge Shado, and almost kills Ollie.
William Tockman, the Clock King, in "Time of Death". A meticulous planner and creepy master thief who, regardless of his ostensibly noble motivation, will stop at nothing to get what he's after, and even hacks the Foundry's computers and makes them blow up while Felicity and Diggle are still inside. Talk about Paranoia Fuel.
The ending of "Birds of Prey" is pure Adult Fear. Thea goes out alone at night and Slade drives up to offer a ride. And for more Mirakuru-related goodness, we have Roy crushing the shoulder of a guy who bumped him and refused to apologize. Listen closely enough and you can hear crunching.
"Deathstroke": Back on the island, Slade hallucinating Shado when he has Oliver and Sara at gunpoint. Given the role she played as a Morality Chain in past, you might expect her to be the conscience. Nope, she's advising Slade to keep them trapped on the island and go after their families. What's worse? He's still seeing her in the present day.
Same episode: How did Slade get off the island? He swam until he reached land. Not so bad? He got pulled under by the current and crushed against the rocks, which apparently cut his flesh to the bone. He survived and healed thanks to the Mirakuru, but Jesus that sounds painful.
Adding to this, Slade had one eye exposed to saltwater, thus making what happened to him more horrendous.
"The Man Under The Hood": Isabel gets Mirakuru. Slade was a heroic, well-meaning person before he got injected, and it made him a dangerous psychopath, but Isabel was pretty much a sociopath before her dosage. Who knows what this is going to do to her.
Slade's surprise attack on Team Arrow, where he's just waiting for them in the lair and completely wipes the floor with them, makes a pretty effective Jump Scare.
Roy, completely hopped up on Mirakuru and reduced to a near-mindless state, going on a violent rampage and curbstomping everyone who's unlucky enough to come across him, often involving him breaking their limbs and the violent, stomach-churning snaps that go with them. One cop isn't even that lucky, as Roy proceeds to violently shove one of Oliver's arrows right through his gut.
And just to add some And I Must Scream to the mix, Roy also has some It Can Think and Fighting from the Inside moments. He's still coherent to the point he can recall his training, fight off Sara and catch an arrow, and can follow directions as he heads east the entire episode towards Verdant. And at several episodes, he gives several blink-and-you'll-miss-it looks back, as if the Mirakuru's control just died down and he's horrified by what he's doing.
His hallucination of Thea, who begs him to kill her.
This one crosses over with Tear Jerker: Slade's Sadistic Choice and murder of Moira right in front of Ollie, while he's tied up and helpless to do anything about it and his sister is sobbing and crying the whole time.
Which extends into his murder of Moira. If the narrative was from his perspective, then we would see his remorse and hesitation challenged by the hallucination of Shado, who insists Moira be killed. Slade acknowledges Moira's courage, but Not-Shado insists she be killed because sparing her wouldn't teach Oliver anything. Notice how his acknowledging her courage is spoken with a wavering voice, with a look of regret. Now compare that to his tone and expression right before he drives his katana into her heart. He succumbs to Not-Shado, to his darkness, and forces himself to kill Moira for the sake of his mission. But once she's dead, once he see what he's done, his energy is spent, which shows when he frees Thea. He's completely devoid of any emotion, and just leaves.
On Oliver's end, we see him completely break. The promo for the next episode shows he's disappeared on everyone again, just like at the beginning of the season when he went back to the island to grieve for Tommy's death. Unlike Robert's death or Shado's death, where Oliver was forced into a situation he had no control over and therefore had to trudge along to keep surviving, this is a situation he saw coming. It was something he was fully aware of and should have been able to prevent. But once Moira hit the ground and he looked into her dead eyes, he lost it. He was back on the island again. But this time, he'd lost the family he had left behind. To him, there's no hope left. To him, there's no reason for anything.
"City of Blood": Ivo's last "gift" to the world was to purposely give the friendly Peter cancer in order to see if Mirakuru could cure it. With no treatment, the cancer has grown into an easily visible and unsettling-looking infection that's slowly killing him. This makes his own infection retroactive Laser-Guided Karma.
"Streets of Fire": Let's start with the basic horror that a bunch of borderline unstoppable thugs are tearing through the city with the explicit orders to tear as much of it down as possible, and kill as many people as they can.
Especially scary is the fact that, until now, each person who received Mirakuru at least had some kind of goal or order to their actions. Slade is an assassin with a specific plan who seems to have trained himself to control his explosive temper to the point he doesn't just go straight to killing Oliver; Cyrus Gold was operating under specific orders on what to do and carried them out; and Roy is instead a hero in training. These soldiers, however, were just random criminals; they could be drug addicts, petty thieves, or money launderers, but they could also be killers, rapists, psychopaths and sadists, any such brand of evil, and now there's nothing to stop them doing what they can, and while they have their orders, they're unspecific enough to let these people do whatever they want. And there's nothing to stop them attacking anyone they see, or going anywhere they want.
The fate of Deathstroke. Locked away in a secret military prison, presumably without a trial. The Nightmare Fuel comes from that fact this isn't Hollywood ignoring the law/due process/etc, for the sake of storytelling. It's perfectly legal in America for anyone suspected of terrorism (and Slade was absolutely a terrorist, even though he only wanted to "terrorize" one person in particular, he was willing to kill thousands to make his point) to be detained indefinitely without a trial.
Werner Zytle introduces himself to the show by forcing a vertigo dart into the neck of a crime boss, who is shown to see his attacker as an enormous roaring monster protruding from a human body. Zytle can even be heard whistling as he prepares to blow up the resturant and the boxing stadium.
Laurel going completely Huntress in the wake of Sara's death, including slamming the injured arm of another of her target's victims against the rail of his hospital bed.
One of the files Felicity recovered for Ray Palmer was entitled O.M.A.C Project.
Roy's nightmare at the end of "The Secret Origin of Felicity Smoak". He sees that it was him who killed Sara, and given what she said in the dream being exactly what she said when she died (something only the killer would know), would mean that the dream is accurate, and he is the killer, though given the fact he appeared possessed and demonstrated enough strength to throw arrows like darts, implying that he still has Mirakuru-level strength, and has developed some kind of Superpowered Evil Side. But, the really disturbing part? Given his comments about not having much sleep recently, it could mean that this isn't the only time this side has came out.
It turns he's not under its influence and he didn't kill Sara — the very next episode, "Guilty", reveals at the end that Sara's death by arrows triggered his subconscious to push forth the repressed memory of him killing the cop in "Seeing Red". Still frightening, and the Internal Reveal leaves him devastated, but there's no Superpowered Evil Side left.
Oliver's duel with Ra's al-Ghul in The Climb shows just how dangerous a threat the latter is. Oliver has been established as a highly skilled combatant, but even though he's apparently among the best Ra's has fought the Demon's Head still delivers a Curb-Stomp Battle that's very brutal (all while remaining perfectly calm and in control), ending in Ollie's apparent death by being impaled and thrown off a cliff. This isn't even an enemy pumped full of supersoldier drug like Deathstroke was.
Quentin Lance's increasingly unstable mind. He starts off ignoring and distancing himself from Laurel after learning she concealed Sara's death, leading to him shouting at the Arrow. He revives his anti-Arrow task force and sets off to arrest him and everyone associated with him using the full power of the police force. By "Public Enemy," he's so far gone that he's willing to take Ra's al Ghul, a known terrorist and murderer, at his word as long as he gets Oliver Queen behind bars. And when Roy is stabbed after falsely proclaiming himself to be the Arrow, he promptly blames Oliver for that too.
Murmur is quite an unnerving villain, with the mouth sewn shut, the creepily efficient way his gang operate and his ultimate plan: steal cheap industrial diamonds and use them to make diamond-tipped bullets. He then attacks the police precinct, killing several cops.
Deadshot's backstory, where he suffers a horrific bout of PTSD that ends with him pointing a gun at his wife. It's an unnervingly realistic plotline in this comic book show.
Thea getting drugged in order to kill Sara can be akin to/tied as a metaphor for rape. Malcolm drugged and used his daughter's own body for his ends, and that's something that rape survivors can relate to. And the scariest and most realistic part? Most people (even some of the writers) are defending him instead of Thea.
Thea and Malcolm's relationship is a spot on case of EXTREME child abuse. Manipulating your daughter into trusting you multiple times even though they know you're a disgusting person? Check. Killing your son and mentally raping your daughter? Check. Turning your daughter into a human weapon to wipe a blood debt while violating her body with a mind control drug? Fucking. Check.
And the fact that Thea is constantly handed back to Malcolm, HER ABUSER, makes it all the more terrifying. Oliver keeps insisting that he not be killed, for no reason other than that he impregnated Thea's mother. He never considers that she'd be better off with Malcolm dead.
Thea was only 19 years old when she was drugged to to kill Sara. Who drugged her? Malcolm Merlyn, a 55 year old man.
Also doubles as a tearjerker; Thea only wanted to learn how to defend herself and even protect others. She could've gotten that, but she ended up being used and becoming a meat shield for her only parental figure left in her life.
The worst part? Not only does Oliver let Malcolm slide for this, he gives Malcolm control of the League. Just think about the damage Malcolm can do now!
The way that Sara dies- it's terrifying, if you think about it. Shot three times in the stomach and landing back first onto the edge of a dumpster, breaking your back if there's enough force and speed from the fall, and having 3 holes in your stomach And guess what? If the arrows didn't kill her, the fall did.
Ra's murdering Thea. He appears in her apartment out of nowhere, appears to teleport in front of her when she tries to escape, and then curbstomps her without effort before finishing it by stabbing her with his sword. Not only is it like something right out of a horror movie, but he's just so cold and efficient about it.
Nyssa being forced into a heterosexual marriage is nightmarish for rather realistic reasons: A LOT of queer people are forced to be straight to protect themselves, and Nyssa being rather open (though not calling herself queer) about her sexuality has had a rather big consequence towards her status as an heir and causes her to be disowned (along with her being a woman).
A meta example, Ra's wanting Nyssa to produce an heir for him sounds a lot like rape. One of his lines is "You will have no say in this like how your mother didn't," possibly stating that Ra's may have raped Nyssa's mother to produce an heir. As well, it does seem that if Nyssa was to produce another female heir, Ra's would have that heir raped as well for his male heir, which shows off that while Ra's may be polite to a fault with most people, get on his bad side and he will never forget.
The line also points out that Ra's is expecting and willing for Oliver to rape Nyssa for an heir** The line also points out that Ra's is expecting and willing for Oliver to rape Nyssa for an heir.
In the penultimate episode, Team Arrow, along with Malcolm and Ray are captured, and in order to prove his loyalty to the league, Oliver, or rather Al-Sah-Him, is told to kill them all...which he does without hesitation by exposing them to the Omega virus. The team desperately pleads with Oliver, but he just walks away as the gas seeps into the room. At this point it seems Oliver has completely crossed over to the Dark Side. [[Thank god it's Subverted in the next episode]]
In "My Name Is Oliver Queen", the flashbacks show the aftermath of an absolutely horrific bout of Cold-Blooded Torture instigated by Oliver on Shrieve. Tatsu shows horror at this.
"The Candidate" has more than a few... erm, candidates.
Thea showing a far more violent side due to the effects of being revived in the Lazarus Pit. She nearly breaks one person's arm and eventually winds up setting Lonnie Machin on fire with a look of almost pure sadism in her eyes. Even worse is Thea's horror after snapping back to normal, as if these violent turns are her literally turning into a completely different person.
Speaking of Lonnie Machin, the man is an Axe-Crazy torturer who loves every minute of his work. Even after his aforementioned case of being lit on fire he still effortlessly ends up breaking out of the ambulance he's in and slaughtering everyone else inside it. He's so ruthless, uncontrollable, and sadistic that even Damien Darhk eventually ends up wanting nothing to do with him.
The very last shot of the episode? Laurel opening Sara's coffin, showing her emaciated corpse.
In Restoration, Sara coming back to life, well Sara's body coming back to life. She's a feral woman snarling at everyone who comes near her.
Damien Darhk is all around terrifying. Imagine a man with not only telekinesis, but the ability to drain someone's life force with just a touch. Not someone you would want to be around. At. All.
John Consantine regularly faced down demons without flinching in his own series. When Oliver tells him Damien's in town, his only advice is to get the hell out of Star City.
Sara after her resurrection. She's worthy of the name Animal Sara at this point. The demonic chanting, crazed, feral movements and constant snarling and yelling are absolutely terrifying, especially when her raw ferocity manages to overwhelmed both Oliver and Laurel at the same time.
Where Sara's soul is kept is a combination of both The Underworld and Basically someone's personal purgatory. Along with that, Sara's desperate attempts to climb out of the pit only to be dragged down by what seems to be numerous pairs of hands that belong to the dead... Also another Note: Don't follow the voices.
Vandal Savage nuking Central City, complete with seeing Oliver and the rest of the cast being reduced to skeletons and then into ashes. True, Flash undid it with his time-travel jump but still seeing it happen was gripping.
A HIVE member conferencing from Spain questions if Darhk's wife can make her campaign for mayor work. Darhk then talks about how he was once in the man's office and can remember every detail. The camera cuts away from the conference screen, but the the sounds we here are absolutely disgusting.
William being kidnapped in Arrow S 4 E 15 Taken has demonstrated every parent's worst nightmare. You can see how desperate and distressed Samantha became when she mentioned how she called the Central City Police Department, and they still can't find her son after 48 hours.
Alex's Gaslighting of Thea on their "vacation," refusing to admit that anything could possibly be wrong and constantly telling Thea she's just being paranoid. It's a much more psychological level of horror than the show usually goes for, and all the more unnerving for it.
All of "Monument Point", which is a frantic race by the now greatly limited Team Arrow to prevent The End of the World as We Know It, with H.I.V.E. seeking to stop them at every single turn. They only end up delaying it, and one nuclear warhead does detonate, killing tens of thousands of people. And Felicity now has to live with that guilt for the rest of her life.
Prometheus, the apparent Big Bad for season 5. Whoever he is, he can easily kill trained cops and hardened criminals, presents himself as even more of an Evil Counterpart to Oliver than Merlyn, and has a serious grudge against the Green Arrow. And, as of "Human Target", he knows that Oliver is the Green Arrow.
A major twist was revealed on an episode of TheFlash when Barry discovered that an aftereffect of the altered timeline he created was that baby Sara was wiped out of existence and replaced by John Diggle Jr. In other words, Digg and Lyla have no idea they had a daughter instead of a son and can't even mourn a child they never knew existed.
From "Human Target", we have Prometheus' curb-stomping roughly a dozen cops, slaughtering them with ease. That the fight goes on off-screen— we hear it all from Church's perspective, and the previously smug Church is terrified— just makes it worse. When the audience is finally shown the results, every cop is dead, Prometheus doesn't have a scratch on him, and he walks towards Church completely unchallenged.
Vigilante in general shows just how bad it would be if Oliver decided to kill without restraint not only does he kill criminals whether they be petty or high level but he is also perfectly fine with killing innocent civilians and writing it off as "collateral damage" unlike Oliver in Season One and Two who only killed those who deserved and still put the lives of innocents ahead of killing a target.
Invasion: Arrow's episode is filled this:
Oliver and Sara remembering the horrifying events in their life; namely seeing Laurel in her hospitable gown. Doubles as a Tear Jerker.
"Deathstroke" attacking Oliver and Diggle at the Queen Mansion. The music during this scene does not make it any better.
When the group tries to leave, they are confronted by Malcolm Merlyn, Damien Darhk, The Ghosts, Deathstroke (again), and the Deathstroke goon. Each attacks Thea, Sara, Diggle, Ray and Oliver not only physically, but psychologically: Malcolm brainwashed Thea into killing Sara, Darhk killed Sara's sister, Deathstroke killed Oliver's mother and nearly destroyed his city, the Ghosts turned Diggle's brother Andy, and the Deathstroke goon killed Ray's fiancee. This really was an example of facing their worst nightmares.
The fact that the Dominators were aware of their weaknesses and used them the way they did...
The Flashbacks in episode "What We Leave Behind" to season one Oliver is a jarring and frightening reminder of just how ruthless Oliver was at the beginning of his vigilante career as we see him shoot mooks who are already down.
Meta example: Felicity, despite being a light-hearted character within the show, has huge emotional issues such as Anxiety and Abandonment Issues that have either spawned from working with Team Arrow or her Childhood. Now imagine what will spawn from being forced to kill tens of thousands of people.
In the scene in "What You Leave Behind" where Oliver confronts Prometheus, there are murdered mooks all over the building. Thing is, those guys can't have been the same guys that Oliver killed on his original mission to take down Justin Claybourne four years earlier. So what that means is that, whoever Prometheus was, he captured, murdered, and arranged the bodies of at least a dozen people to imitate Oliver's original crime scene. Just to make a point. Also consider that he may not even be Claybourne's son at all, meaning he may be going to commit even more extreme killings to go after Oliver in the future.
Want to know something even worse? If you rewatch the scene a few times and pay close enough attention, you'll see that most, if not all of those mooks look like the ones Oliver when he took down Justin Claybourne. And knowing how crazy obsessed Prometheus is about this whole thing and how actually depraved he is, it's entirely possible, and would be completely in-character, for him to just go around and kidnap random people off the streets, shoot them with arrows, and place their bodies in the spots of the mooks Oliver killed, just for the crime of looking like them and quite possibly having the same profession as them.
In "Who Are You?" Prometheus is revealed to have break Black Siren out of the STAR Labs Pipeline without anyone noticing. STARS Labs security maybe a joke, but the Pipeline is the one alarm that always go off, Prometheus was able to bypass all alarms. And since Black Siren has knowledge of the Waverider and Sara, it implied that he knows about every hero in the verse and all of the inherent weirdness in it.
The shootout of The Mayors office is incredibly frightening. Unlike other episodes where there was a feeling of reassurance knowing the Oliver as the Green Arrow will show up eventually ( which he can't because he's already there being guarded himself). This time their is none of that and we are shown what it is like to be at the mercy of a madman with a firearms.
Just the entire episode of "Checkmate" is this. Throughout the entire episode Chase manages to one up Oliver in every move he makes to stop him and unlike previous episodes where Oliver at least had the advantage of his enemies not taking his team into account Chase knows everything and everyone associated with Oliver. By the end of the episode He has Oliver captured and is ready to break him physically and mentally.
Kapiushon ranks up as one of, if not the, most terrifying episode of this entire series. Not only is it the torture that Chase puts Oliver through for six days or seeing him snap Evelyn's neck (it was a staged but still) but the fact that Chase breaks Oliver by revealing the one secret that Oliver has kept from others and even himself: that Oliver likes killing people and unlike previous times in which others have accused him of being a killer Oliver has his most genuine Heroic BSoD because he knows in his heart that it is true. Even more disturbing is the fact that Adrian lives up to his promise to let Oliver go once he revealed his secret. Unlike Slade whose plan to break Oliver involves killing the people he cared about Adrian's simply has Oliver admitting what he can't bring to tell himself.
The flashbacks effectively serve to illustrate exactly what Adrian is talking about, particularly when Oliver tortures a man for information and then after the man has given up the information, Oliver tortures him further "for practice", until the man dies. Ultimately, while Adrian is a terrifying villain, the most horrific aspects of this episode are seeing the depths of moral depravity that our hero has gone during his ten year journey, ultimately serving to make the viewer uncomfortable with the protagonist we've been following for five seasons.
Poor William. In the span of a few days, he's been kidnapped, taken to a strange island, been separated from his mother, reunited with his father, learned his father is the Green Arrow, and seen his father's worst enemy shot in the head. How much therapy is he going to need for the next few days, and who knows whether he'll be the same.
Cayden James, the leader of Helix. The man is utterly chilling and is perfectly capable of killing 3% of the world's population with only a few strokes of a keyboard.
He also orchestrates a bomb threat just to talk to Oliver as the Green Arrow- with two side benefits. One, his mooks are dressed like cops, and footage of them fighting Team Arrow makes the city outlaw vigilantes; two, he still has a bomb. A thermo-baric bomb to be precise, which is capable of "pressure cooking" an entire stadium's worth of people.
The flashbacks of Slade in episode 6, showing him at the height of his Mirakuru insanity and then finding out that Oliver is still alive. He then proceeds to slaughter an entire ASIS training compound and even comes dangerously close to murdering his own son. Just as a friendly reminder for the viewer just how utterly terrifying he was during that time period.
Slade assumed Joe followed in his footsteps after reading about his rampage as Deathstroke and is trying to convince him it was because of the Mirakuru. Then he finds out Joe saw him kill a Chinese agent when he was a kid...and made his first kill six months later. Slade is horrified to realize his son has always seen him as a monster and because of that, Joe turned into one himself.
Cayden James' Reign of Terror. He manages to hack everything in Star City with an Internet connection causing mayhem including crashing a freaking a plane. He demands $10 million a day for an indefinite period to stop the chaos. He doesn't want the money, he just wants to ruin Oliver's life. In the end Oliver gives him the money, because he can't stop him.
The Reveal that Cayden James isn'tThe Big Bad, merely The Heavy. The person who sent him the "evidence" of Green Arrow murdering his son is the same person who leaked the doctored image of Oliver as Green Arrow to the press. That's right somebody out there set an insane Cracker lose on Star City all to destroy Oliver. And if Cayden some how doesn't do it, Agent Watson has all she needs to put Oliver away behind bars. And we absolutely have no idea who this person is.
During All for nothing there is the real unsettling sight of a good dozen A.R.G.U.S. divers being electrocuted underwater.
Just 'imagine having to learn that your only son got murdered while you are imprisoned alone in a dark container, like Cayden James had to, as revealed in The Devil's Greatest Trick.
The return of ADRIAN CHASE. While Oliver's in the bunker, he just shows up without warning, attacks Oliver and nearly kills him. Oliver eventually gets him in a headlock, prompting Chase to goad him into finishing it less he lose more loved ones. So Oliver kills him. He then takes a breather only to find that Chase's body is gone. Chase then reappears in front of Oliver, revealing himself to be a hallucination.
The scary part is not the fight itself. It is the fact that Oliver was willing to kill Adrian Chase this time. In other words, Ricardo Diaz successfully succeeded in pushing Oliver over the line... which exactly what Chase was trying to accomplish.
The Star City Slayer aka Stanley Dover is absolutely terrifying. He somehow finds out about all of Oliver's friends, where they live, where they work and leaves threatening notes for them, then slashes Dinah's throat when the group is investigating his creepy lair, paralyzes Oliver and his family and almost manages to kill Felicity. To say nothing of his backstory...