Mysterio

Mysterio is the moniker of Quentin Beck, a special effects expert with aspirations for acting.

Biography
At some point in his life, Beck put his talents up for hire and teamed up with the Chameleon and Phineas Mason.

It's unknown how long Beck has been in league with the Chameleon, but judging by their dialogs, they seem familiar with each other and may have worked together on several assignments.

They trio was assigned to steal the symbiote from the Empire State University Bio-Genetics laboratory. Their plan fails but the alien substance goes missing and Spider-Man gets the blame, so the Chameleon decides to take that to their advantage. He goes on a crime spree posing as Spider-Man, and Beck uses his special effects expertise to convince every eyewitness that the Chameleon is the real webslinger.

During a party hosted by Mayor Water in an ocean liner, the team of crooks infiltrates the crew, with Beck posing as a waiter. He knocks out the guards with drugged coffee and the Chameleon sequesters the guests' belongings. When the real Spider-Man foils the robbery and knocks the Chameleon down, Beck sneaks up behind him and drops an exploding demitasse, proving cover for the trio to escape. Just as Beck and Mason are about to jump aboard their escape Jet Ski, Black Cat pulls them up and knocks them out. Beck is arrested. ("Persona")

The Mighty Mysterio
Sometime afterward, Beck gets out of prison and is enlisted by the Master Planner. At his behest, Beck sets out to steal assorted technology from Tri-Corp and OsCorp. In order to do so, he adopts the alias of Mysterio. Donning a theatrical costume with built-in remote controls and using a wide range of special effects technology, Mysterio poses as a real life sorcerer.

Firstly, he makes an appearance at a shipping site, introducing himself as the master of the arcane arts set out to rid mankind for the evils of technology. He spouts Latin incantations to bring his baffled spectators on their knees and disappear with some hardware. He then appears on a bridge to steal the cargo from an armored car. He conjures a flying serpent to scare away the mob. At that point, he is intercepted by Spider-Man and saps his strengths. He moves in wielding a sword, but the webslinger disarms him. Mysterio commends his strength of will before blasting him with lightning. He then levitates the armored car and drops it down the river. While Spider-Man takes a plunge to save the driver, Mysterio slips away with the cargo. Afterwards, he breaks in OsCorp. He uses his illusions to dispose of the security and as Spider-Man comes in, he unleashes a flock of mechanical homunculi to ward him off. Once again, Mysterio slips away with the cargo, although this time he was followed by Spider-Man. He arrives at his lair, and analyzes the plans for his next target. Spider-Man had uncovered his pretense and sneaks up on Mysterio, but he evades him. Mysterio takes on Spider-Man with all his trickery, illusions, and robots. At some point, Beck runs for shelter, leaving a mechanical replica in his place. When Spider-Man unmasks and apprehends the fake Mysterio, "Beck" reminds Spider-Man he was the Chameleon's right hand man in the ocean liner robbery. Spider-Man arrests "Beck" and calls the police.

After everyone clears off, the Tinkerer informs the real Beck he can come out from his hideaway and scolds him for making his decoy in his likeness. Beck declares that he didn't want anybody else taking credit for the role of "Mysterio." ("Blueprints")

The Sinister Six
The decoy is thrown to prison, where he shares a cell with the Vulture. When the Master Planner issues the rallying of the incarcerated villains, the robot seemingly provides a hologram of the Vulture, after he was somehow extricated.

Mysterio is later summoned to the Master Planner's lair to join his new Sinister Six. When the Master Planner expresses his disappointment at Doctor Octopus' refusal to enroll his Sinister Seven, Rhino exclaims that there are seven villains in the room, counting with the Tinkerer. Mysterio, however, guarantees that he is only good for technical support, utterly useless in combat. The Master Planner goes on to announce that his new Sinister Six will help him to usher in the era of the super criminal, after they dispose of Spider-Man. After the Times Square debacle, the Master Planner employs a new strategy consisting of dividing the group into teams of twos.

After the Vulture, Electro, Sandman, Rhino had been subdued, Mysterio and Kraven the Hunter engage Spider-Man. They chase him down to a shopping mall where Mysterio unleashes a flock of homunculi. Mysterio then sets a decoy to lure Spider-Man. However, when he tries to warn Kraven, Spider-Man realizes this and runs for shelter. Mysterio tries to elude Spider-Man with his tricks, but gets snared by his webbing. Spider-Man unmasks Mysterio, who surrenders and vouches not to be robot. Spider-Man asks him who the Master Planner is and what he wants with the tech he stole. Mysterio taunts the webslinger saying that perhaps the Master Planner has a "master plan." Mysterio is then taken into custody. ("Reinforcement")

While in prison, Beck is interviewed by a Daily Bugle reporter about Spider-Man's recently revealed identity. Beck says he is hopeful that Peter really is Spider-Man, as everyone in prison would know what to do with that information. ("Identity Crisis")

Shortly after, Montana is arrested and put in Beck's cell. There, he finds out that Beck is actually a robot. It remains unknown whether Beck was a robot when Spider-Man arrested him or he escaped prison at some point somehow. When Spider-Man is trapped inside the prison to test the Vault's security system, the Green Goblin releases the prison's inmates. Montana activates a switch on Beck's back, turning him into Mysterio. He attacks Spider-Man with energy blasts and his homunculi. Rhino and Molten Man eventually join the hunt, and Spider-Man tricks Molten Man into destroying Mysterio with a lava ball. The whereabouts of the real Quentin Beck remains unknown.

Role in Ultima
In Ultima, Mysterio is.