Beck was originally one of the Chameleon's partners in crime. He is described by the Chameleon as being a master of special effects and illusions. He is arrested along with Phineas Mason at the end of the episodes while Chameleon escapes.

Beck becomes Mysterio in "Blueprints." He robs various technologies (ranging from technology that was to be shipped to the labs at ESU, an armored car, TriCorp, and OsCorp) using his illusions while claiming to be a sorcerer. Spider-Man followed him to his hideout and his cold gave him away when trying to find out Mysterio's identity. Spider-Man used a web blindfold to let his Spider Senses tell him which is real and which is not. Mysterio then summon robotic duplicates of himself to attack Spider-Man. However, Spider-Man handily defeats the majority, then deactivates the other with Mysterio's remote control glove, breaking it.

Mysterio unmasks himself upon his defeat, but finds to his frustration that Spider-Man barely remembers who he is, he had to recap that he was Chameleon's henchman before Spider-Man restrains him. However, it turned out to be another android as the real Mysterio was hiding during the conflict. After the cops leave, Tinkerer talks to Mysterio about the design to his android to make it look like him. Beck tells him that he holds the trademark to that name, and is outraged at the idea of someone else taking the credit for being Mysterio. It is revealed that they worked for the Master Planner.

At Ryker's Island, the guard discovered that the Quentin Beck they have is an android after they found an illusion of Vulture (his cellmate, apparently). Mysterio joins the new Sinister Six under the orders of Master Planner. He and Kraven the Hunter battle in a mall where a Mysterio duplicate accidentally takes out Kraven. He attempts to escape by turning invsible, but a webbing net over the floor pinpoints his location. Spider-Man ensures this isn't another android double and tried to get answers on who the Master Planner is, but Beck was close lipped (or quite possibly, didn't know himself). Mysterio was seemingly arrested while the other villains were extracted at the last minute, though it was later revealed, as Spider-man suspected, the Mysterio arrested was another robot.

An imprisoned, robotic Beck is later interviewed by Ned Lee. He expressed some doubts that Peter Parker was Spider-Man, but stated in no uncertain terms he and the other inmates at Ryker's would know exactly what to do with that information if it was true, which he hoped was.

The robotic Beck was 'unmasked' by his cellmate Montana during Spider-Man's imprisonment in the Vault, and proceeded to unleash his customary attacks against Spider-Man. Spiderman yelled "I knew he was a robot, I knew it", when he learned it really was a robot. it was later fried by a misfired fireball thrown by the Molten Man.