The Sinister Six are a group of supervillains in the Marvel Comics universe, who serve as a collection of Spider-Man's foes. The original incarnation of the Sinister Six was organized by Doctor Octopus and appeared in The Amazing Spider-Man Annual #1 (1965).
After suffering three defeats in a row from the wall crawler, Doctor Octopus realized he required assistance from others in order to defeat Spider-Man. After his recent defeat followed by the police successfully removing the tentacle pack, Doctor Octopus mentally controls his tentacles to come to him and he escapes from jail. Afterwards, he contacted every known supervillain that had crossed paths with Spider-Man, but only five responded: the Vulture, the electrifying Electro, Kraven the Hunter, master illusionist Mysterio, and the Sandman. Knowing he'd never be able to keep the team together for long, Doctor Octopus quickly formulated a battle plan in which each individual member of the Sinister Six would battle Spider-Man in a carefully chosen location, giving each of them personal glory and Spider-Man an early death.
Spider-Man himself had his own problems, as he had somehow lost his powers and prepared to return to normal life as a teenager. While blaming himself for the death of his Uncle Ben, Spiderman lost his balance and fell down the side of a building, ending up clinging to a flagpole. As Peter returned to his normal life as a student and a freelance photographer, he was unaware of the fact that the Sinister Six realized the Daily Bugle secretary Betty Brant played a large role in Spider-Man's life and kidnapped her, along with an innocent bystander—Aunt May. It was then left to the Vulture to spill the beans to J. Jonah Jameson, warning him to inform Spider-Man that Betty was being held hostage along with Aunt May and if he wanted to see them alive, he'd have to battle the Sinister Six.
Despite not having his powers, Peter put on his Spider-Man costume and went to fight Electro at an electrical plant. During the battle, Peter somehow regained his superpowers (the loss was speculated to be caused by his own self-loathing for the loss of his uncle, which he got over when facing a life-or-death situation) and easily defeated Electro. Spidey then battled against Kraven—who confronted him with some wildcats—and defeated this foe too. After defeating Mysterio, Sandman and the Vulture, Spidey went up against Doc Ock, who lured him into an enormous fishbowl. The two foes battled and Spider-Man was victorious.
In Marvel Knights Spider-Man, Norman Osborn, the Green Goblin, had been unmasked to the public and imprisoned after losing a battle to Spider-Man. Defeated but unbowed, Osborn concocted a fiendish contingency plan. He contacted a group of supervillains who also bore grudges against Spider-Man, and all of them had been financed by Osborn's fortunes for years. (It was revealed that most supervillains have corporate funding in the Marvel Universe). Eager for revenge, the villains agreed to band together, and the Sinister Twelve was formed.
The Sinister Twelve was the largest gathering to date of Spider-Man's enemies. The major villains not part of the Twelve were either deceased (Mysterio, Kraven the Hunter), retired (Molten Man, Hobgoblin), incarcerated (Rhino and Doctor Octopus), or simply too unpredictable and insane to be trusted (Carnage).
Mac Gargan, the Scorpion, was the de facto leader of the Twelve while Osborn was in prison, and it was he who kidnapped Peter Parker's Aunt May and threatened to kill her if Spider-Man did not help Osborn escape from jail. A desperate Spider-Man, with help from the Black Cat, broke Osborn out, only to be confronted with the Vulture, Sandman, Electro, Chameleon, Lizard, Hydro-Man, Shocker, Hammerhead, Boomerang, and Tombstone. Osborn, now in the guise of the Green Goblin, introduced them as the Sinister Twelve. The final member of the group, Scorpion, shocked everybody present when he arrived, revealing that he had bonded with Eddie Brock's alien symbiote, becoming the new Venom. Although Osborn was displeased with Gargan's new power, he nevertheless watched with glee as the assembled villains converged on the hopelessly outnumbered Spider-Man and Black Cat.
Despite the odds, Spider-Man and the Black Cat fought back in a heroic last stand. Before the two could be killed, salvation arrived in the form of Captain America, Iron Man, Daredevil, Yellowjacket and the Fantastic Four, who struck back at the villains. Spider-Man's wife, Mary Jane Watson, had called S.H.I.E.L.D. to aid him, as she feared he was heading into a trap. A furious Green Goblin rocketed away and kidnapped her, and Spider-Man pursued him, fighting off Venom, who was trying to stop him. Spider-Man and the Goblin clashed once again upon a bridge (not the one where Gwen Stacy was killed), this time with Mary Jane's life at stake.
Finally Osborn gave a vital clue as to Aunt May's whereabouts, and was defeated by a combination of being shot by Mary Jane, struck by lightning, and attacked by Doctor Octopus, who was brainwashed by the police into trying to kill him. The Goblin fell into the river below, and Aunt May was found and saved.
In the aftermath, Peter received a pre-sent letter from Osborn, thanking him for all the "excitement" their rivalry has provided over the years and telling him to rest easy until they meet again. The rest of the Sinister Twelve were subdued by the heroes and arrested; Gargan ended up, ironically, in Osborn's old cell.
With this equipment, Fiers planned to trigger a massive electromagnetic pulse that would blank out all databanks in Manhattan- the only reason he ever risked working with loose cannons like the Six in the first place was because Electro's powers were the only way he would have the energy to trigger the pulse-, subsequently releasing the catalyst to destroy all ink in New York, triggering a complete financial collapse due to all the documents and information lost- to say nothing of the anarchy that would result as gang warfare became the only way to survive-, while the Gentleman's own recently-purchased material wealth would significantly increase in value. However, Electro, the Vulture and Mysterio were all taken out before Electro could trigger the pulse, Doctor Octopus and the Chameleon both attempted to betray the Gentleman and take control of his plan, and Pity was convinced to help Spider-Man defeat her two former teammates when he reminded her that Octopus always hated not being in charge. Fiers subsequently died of gunshot wounds caused when the Chameleon attempted to take his place (only to be caught by Octavius), the Chameleon ended up in the hospital due to hypothermia after the Gentleman's plane crashed into cold water, Octavius vanished for a time, and Pity disappeared, with her final fate remaining unclear.
Scorpion was tossed out a window and presumably killed by Spider-Man, and Electro and Hydro-Man were killed when Spider-Man caused the two to fall onto each other. Spider-Man defeated both Kraven and Mysterio and left them webbed up.
After his long-lost daughter was killed by the Reign, policemen under Waters' control, Sandman confronts Waters who gives him the detonator. As Spider-Man is battling a series of Venom symbiotes, Sandman gives him the detonator before allowing himself to be devoured by the symbiotes. Spider-Man presses the detonator, causing the rest of the Six to presumably explode.
In the 1994 animated series, the Sinister Six was called the Insidious Six. Fox Kids censors felt that the word sinister sounded too menacing for a children's program (even though another Fox Kids children's program, X-Men had Mister Sinister as a villain). The Insidious Six was formed in the beginning of Season 2 as a two-part episode premiere, it was created by the Kingpin to settle off his debt with his enemy, Silvermane, and consisted of Doctor Octopus, Mysterio, Shocker, Chameleon, Rhino and Scorpion to kill Spider-Man. Initially the Six fought and overpowered Spider-Man but the hostilities between them prevailed and Spider-Man escaped. They tried to lure him out but Spider-Man did not respond because at that time he suffered from a mutation disease that caused him to slowly lose his powers. Then, assuming that Spider-Man and Peter Parker were friends, they kidnapped Peter Parker's Aunt May without having her know she was kidnapped, and told Peter that if Spider-Man didn't come to them on time, they would do horrible things to her. When they fought Spider-Man inside a warehouse, they easily defeated and unmasked him, discovering he was Peter Parker. However Spider-Man's poor performance (due to his disease) led Dr. Octopus to mistakingly believe that this wasn't the real Spider-Man and that Peter Parker, unable to find Spider-Man, donned a Spider-Man costume and tried to save his aunt. Using this opportunity to keep his identity hidden, Peter lied that he was indeed not Spider-Man. He also managed to steal some of Mysterio's holo-cubes. The Insidious Six then warned Peter that if he didn't take them to see the real Spider-Man, they would hurt Aunt May. Peter then took the Six to the top of a roof and changed into Spider-Man without them knowing. Then, using his brain and Mysterio's holo-cubes, he managed to take advantage of the hostilities between the villains causing the Six to disband. The Insidious Six return in the only five-part and longest saga in the Spider-Man series, Six Forgotten Warriors. The title of the saga has a two-way meaning since the, now aged, American Six fight the Insidious Six. Kingpin has once again recruited the Six to help him acquire the keys of the American Six that activate the Doomsday Device. The Vulture (with his youth regained) had replaced Mysterio in this group because Mysterio had died in the explosion of his own studio in the episode, The Haunting of Mary Jane. With Kingpin participating in most of their missions and coordinating their actions, the Insidious Six succeeded. They managed to collect the keys and they defeated Spider-Man and the American Six. However, as the Six unlocked the door to the Doomsday complex, Chameleon released a sleeping gas knocking out his teammates, Kingpin and the captured heroes. It was then revealed that Chameleon was the stepson of the Red Skull and his allegiance belonged to him and not to the Kingpin. After that the Red Skull was freed from his prison (the Vortex) by Chameleon and Rhienholdt Kragov, the Red Skull's son. Later, Captain America emerged from the vortex and, in the ensuing battle, a part of the complex collapsed along with Kingpin's ambitions for world domination. Then Chameleon joined his father, the Red Skull, while the rest of the Six disbanded once they realized that there was no profit to be made.
The Sinister Six appeared in episode 11 titled "Group Therapy" consisting of Doctor Octopus, Sandman, Shocker, Vulture, Rhino, and Electro. Like in the original version of the team, Dr. Octopus is the leader of the team. The team's members have all previously been members of the Sinister Six previously in either the comics or other animated Spider-Man programmes.
The villains pooled their resources and organized a well-planned jailbreak orchestrated by Hammerhead on Tombstone's orders, then went after Spider-Man. After realizing that his previous strategy's wouldn't work, Spider-Man beat a hasty retreat. Going to bed that night, he wished that he could wake up tomorrow and see the Six back behind bars. The black suit, like a malignant genie, took over his body as he slept and met Dr. Octopus and his team. Spider-Man--or, specifically, the symbiote acting as Spider-Man--defeated all six handily, using both a few new tricks which were previously impossible in his standard blue-and-red costume and the Six's own talents and weaknesses against each other. Peter later awoke, bone-tired, late in the day to find his idle wish had been granted. The Bugle reported the Sinister Six has been captured, and his own byline below photos of the battle stared him in the face. He realized the symbiote suit was "wearing me" and was horrified.
Of note is that the team never actually uses the codename "Sinister Six" amongst themselves; it's only used in the Bugle headline reporting their defeat and capture.
In Season Two, Mysterio and Kraven will become new members of the Sinister Six, just like the original round up roster in the comics.
Spider-Man 2: The Sinister Six was released in 2001 for the Game Boy Color, the Sinister Six consisted of Doctor Octopus, Mysterio, Sandman, Vulture, Scorpion, and Kraven.
Spider-Man: Friend or Foe featured a Mysterio-controlled Sinister Six which consisted of Green Goblin, Scorpion, Doctor Octopus, Rhino, Venom, and Sandman.