Peter Parker himself has many dark counterparts among his Rogues Gallery.
Mac Gargan aka Scorpion. Both are based on arachnids. Both are have Super-Strength and are extremely tough. Both gained their powers in a laboratory. Both started off as The Everyman, being working class and were happy enough to just to make money upon getting their powers. Where Spidey and Scorp deviated was that Gargan never got passed selfishness Peter had at the beginning of his career; in fact he reveled in the strength his powers brought him and started doing crimes the moment he defeated Spider-Man in their inital bout. Later comics detail how Spider-Man and Scorpion are ultimately Dude, Where's My Respect? hard-luck types looked down upon by their peers, with Miles even learning Gargan ironically has a similar life to Peter — just superheroism replaced with supervillainy. Plenty of characters point out to Gargan that if he just let his vendetta with Spidey go, he might actually be a decent hero but sadly Chronic Villainy means Scorpion can't make any choices that aren't self-absorbed or petty. Norman Osborn even has Mac impersonate Spider-Man and serve as his counterpart on his first Dark Avengers team.
Norman Osborn aka Green Goblin. Both Spidey and Norman had troubled childhoods and were "created" in a Freak Lab Accident. Norman desires power and fame above all else, something Peter also sought when first donning the Spider-Man costume. However, a certain incident with Uncle Ben taught Peter responsibility, something the Green Goblin cannot comprehend as his whole life has been driven by selfish desires and he never takes responsibility for his actions. Outside their costumes both Peter and Norman are men of science, becoming CEOs of their own companies before losing them, though they still use their scientific expertise to save/hurt people. Spider-Man and Goblin also make a habit of ruining each other's lives, whether by killing the woman they both desired or framing each other. The biggest difference is that while Peter is capable of moving on with his life, Norman can't let go of his crazed hatred of the wall crawler. When Norman bonds with the Carnage Symbiote and becomes Red Goblin he is the evil counterpart to symbiote Spider-Man in the same vein that Kletus Cassidy was to Eddie Brock. While symbiote Spidey holds back despite the immense strength boost the alien suit gives him, Norman revels in the power and lambastes Peter for his morality, saying there's no killer in him.
Otto Octavius aka Dr. Octopus. Like Peter, he's a bespectacled science nerd who was bullied in his youth, and grows up to take on a costumed alter ego based on an animal with eight legs. The comparisons become more overt during Superior Spider-Man (2018), where Otto takes over Peter's body and usurps his role as Spider-Man, becoming a tyrannical figure who spies on the people of New York and enforces his will with a private army of armed minions and giant mechs. The whole run is essentially a What If? story showing us what it might look like if the mantle of Spider-Man was assumed by someone with all of Peter's willpower and scientific skills, but none of his idealism or sense of responsibility.
Eddie Brock aka Venom. Venom was created when the Venom Symbiote, formerly bonded to Peter, found a new host in Brock after Peter cast it aside. Due to having been a part of Peter, the symbiote grants Eddie all of Peter's powers and memories, and as Venom Eddie dons a costume almost identical to Spider-Man's, only colored black. The pair are even mirror images of each other in their civilian identites, as they both work for news agencies, though Peter is honest with his journalism while Eddie Brock's corrupt methods got him fired.
Max Dillon aka the Shocker. Like Peter, Electro was a nobody who suffered a freak accident that gave him superpowers, and upon getting his powers he used what scientific skill he had to fashion himself tools and a costume. Unlike Spidey however, Electro has no Jerkass Realization and in fact as he claims to Magneto, he views the lightning strike that gave him powers as "karma" giving him the chance to take revenge on anyone that makes him feel small and worthless. In essence having the same attitude Peter did when he got his Spider powers, yet never getting better like his nemesis did. Adaptations such as Spider-Man: The New Animated Series and The Amazing Spider-Man play this even straighter with Electro being a With Great Power Comes Great Insanity figure who was once a wallflower like Peter was.
Richard Deacon aka Human Fly. A loser changed into a invertebrate-themed superhuman in a bright costume with great strength, toughness and Wall Crawl powers. Peter even notes their similarities when they first fight, adding that he hates being imitated. Except where Peter was a innocent person before getting his powers, Deacon was already a despicable criminal who almost killed a woman in a hostage situation and unlike Peter has no altruism whatsoever.
The sixth Hobgoblin, Phil Urich. He's a young, up-and-coming photographer for the Daily Bugle (serving as Peter's replacement when he left to work at Horizon Labs), he balances his job at the Bugle with a costumed alter ego, and as the nephew of Peter's old mentor Ben Urich, he even has an "Uncle Ben". But while Peter fights crime on the side, Phil commits it; and while Peter got his powers by accident, Phil personally paid the original Hobgoblin (Roderick Kingsley) for the right to use his name, costume and equipment.
Blood Spider was trained by Taskmaster to copy Spidey's moveset in order to kill him. His two teammates, Death-Shield and Jagged Bow, are similarly trained Evil Counterparts for Captain America and Hawkeye.
Herman Schultz aka The Shocker, surprisingly enough. Like Spidey, Shocker is a working class loser in a fullbody outfit who has to cobble together his own equipment and when it comes to the greater Marvel Universe both are certainly The Chew Toy, having the worst luck imaginable and often get little respect from their fellow costumed-types. They're also both capable of hitting well above their weight class due to people underestimating them. Where they differ is that Herman having had his parents die at early age, never had the same positive influences that Peter did and became a petty criminal as a result. Superior Foes of Spider-Man really has fun with this, as Shocker being the protagonist, he's highly akin to Spidey with their similar mishaps. Also like Spidey, Shocker canonically has his own Thememobile.
Ai Apaec was conceived as an evil version of Spider-Man, wears a black variant of Spider-Man's costume, and serves as the Spider-Man counterpart on the second team of Dark Avengers. However, he has no real grudge against the hero or any meaningful connection to him. In fact, they have only ever faced each other in New Avengers, never in Spider-Man's solo books.
Charlie Weiderman was a nerd picked on through high-school just like Peter, but grew up harboring grudges, while Peter not only forgave but befriended his high-school bully, Flash Thompson. When Charlie gets powers by accident, he immediately goes to exact revenge on anybody who wronged him.
Kaine Parker and Spidercide are two evil clones of Spider-Man created during The Clone Saga. Spidercide gets killed off, while Kaine eventually makes a Heel–Face Turn to become an Anti-Hero.
The Thousand, an old school bully of Peter's who witnessed the accident that turned him into Spider-Man. In an attempt to gain Peter's powers himself, he goes back to the lab after hours, finds the dead spider, and eats it. It turns him into a being capable of becoming a living swarm of spiders. He ends a promising criminal career as a single very ambitious spider who fails to notice a large human foot coming down behind him...and—squash. The Thousand is also an Evil Counterpart to Flash Thompson in that both of them bullied Peter in school. However, whereas Flash was more of a Jerk Jock who was a bully due to his troubled home life and own insecurities, and who also has his redeeming traits, Carl King is a sadistic, psychopathic monster who has all of Flash's negative traits with none of the positive ones. Whereas Flash looks up to Spider-Man as an inspiration, Carl (who knows Spider-Man's secret identity as "puny Parker") resents Spider-Man's strength and powers and wants it all for himself.
Nick Spencer turns Spider-Man into Peter Parker's Enemy Without counterpart and showcases why strength, skill and intelligence is dangerous without responsibility to balance it out. It's quite poignant as bad Spidey doesn't even know who Uncle Ben is and doesn't understand why Peter cares so much about accountability.
Cletus Kasady aka Carnage is Eddie's Arch-Enemy, and a Replacement Flat Character with all of Venom's powers and rage but none of his redeeming qualities. The Carnage Symbiote is Venom's offspring, born when some of the Venom Symbiote mixed with the blood of Kasady. While Kasady was already a psychotic serial killer, after becoming Carnage he revels in his newfound power and seeks to kill even more people.
The symbiotes in general have the Poisons. Symbiotes take humanoid hosts, which they empower; Poisons deliberately hijack this process in order to convert the host into a loyal Poison. Both even tend to mimic the costumes of superhero hosts, although symbiotes tend to be very biological in appearance while Poisons are more crystalline.
Toxin, the spawn of Carnage, is its "father's" Good Counterpart, as it bonds to a police officer who seeks to use its power for good, following Spider-Man's example.
Norman Osborn also becomes an evil counterpart to Nick Fury when he takes over S.H.I.E.L.D. in Dark Avengers as well as an evil counterpart to Iron Man when he dons the Iron Patriot Armor.
Spider-Men II and Miles Morales: Spider-Man (2018) gave Ultimate Marvel universe native (and later immigrant to Earth-616) Miles Morales one in his actual Earth-616 counterpart. Miles was a teenager who was inspired by the death of his universe's Peter to take up his mantle, the Earth-616 Miles was an adult who was also allies and friends with The Kingpin, and after a brief stay in a restored Earth-1610, returns to Earth-616 as the villain Ultimatum.
