Seasons 1–2 (2010–2011)

Five years prior to the events of the series, an explosion occurred on Earth, causing microscopic machines called "nanites" to infiltrate the bodies of all its organic life. When activated, nanites mutate the biology of their hosts; living beings with activated nanites are known as Exponentially Variegated Organisms (E.V.O.). Rex is an amnesiac fifteen-year-old boy and permanent E.V.O. who, unlike most other E.V.O.s, lacks physical deformation but has forgotten his past. He is also able to control his active nanites, allowing him to manifest from his body various bio-mechanical abilities and powers. He also has the unique ability to deactivate nanites inside other E.V.O.s, effectively curing them of their mutations and returning them to normal. Working for Providence under Agent Six and White Knight, Rex uses his unique abilities to stop and cure rampant E.V.O.s.

His archenemy, Van Kleiss, is a British scientist who became an earth-manipulating humanoid E.V.O.. He despises Providence and is connected to the original nanite explosion, which is noted as "the Nanite Event" five years prior. He seeks to become all-powerful by using fellow E.V.O.s, and promises to tell Rex about his childhood past if he will join him, using the former's blooming relationship with the siren-like human E.V.O. Circe to do so. Upon attaining Rex's nanites, Van Kleiss acquires the opposing ability to create E.V.O.s upon physical contact; whereas Rex fully regains his powers and access to new and greater machinery from his Omega-1 Nanite after fully tapping into the further evolved nanite's greater technological abilities.

After her second and final mission with the Pack, Circe defects when Van Kleiss threatens Rex's life and joins his E.V.O. street gang in Hong Kong, China. To further complicate matters, Rex's long-lost elder brother Dr. Cesar Salazar suddenly resurfaces and joins Providence. At one point, Van Kleiss and Rex are forced to work together to escape the artificial intelligence Zag-RS, who is revealed to be a creation of Caesar's who modeled her voice after their late Mexican mother Violetta. Back in Hong Kong, Rex encounters and defeats his former boss Quarry, who was given a proposition from Van Kleiss, but was taken to Abysus for punishment after double-crossing him. Rex's ninja-like partner Six suffers amnesia from a machine of Cesar's invention, but chooses not to regain his memories. In a last-ditch effort to achieve his ultimate goal of becoming a god, Van Kleiss further develops Breach's portal-creating ability, allowing her to travel through time. As a result of her abilities, Rex is sent six months into the future and Van Kleiss is sent to the ancient past. In the future, it is revealed that everything has changed drastically since Rex's "disappearance", and he is shocked to meet a woman in charge of Providence who calls herself the "Black Knight."

Season Three (2011–2013)

Rex is sent six months into the future by Breach's abilities, where everything has changed since his "six-month disappearance" and Providence has been taken over by a woman called the Black Knight. She attempts to manipulate Rex into utilizing his abilities to aid her in "saving" humanity by restarting the Nanite Project with those who had funded it six years ago to become all-powerful by ensuring the creation of five nanites called the Meta Nanites, which contain the "God Code." The first four were scattered across the planet due to the Nanite Event, and the fifth and most powerful one has been kept hidden within Rex himself. Cesar and their late Hispanic scientist parents, Rafael and Violetta Salazar, had secretly programmed them to fully work for him alone.

Upon merging with the God Code, Rex utilizes his newly attained godhood to successfully cure all E.V.O.s. Afterwards, he is reunited with his now-normal friends- Tuck, Cricket and Sqywdd- and girlfriend Circe, and forgives Cesar for his past actions. Van Kleiss, who is revealed to have been responsible for Rafael and Violetta's deaths by trapping them inside as the nanite reactor exploded, is taken to Breach's pocket dimension of Greenville, Ohio.

Main characters

• Daryl Sabara as Rex Salazar, Rombauer (1st time), White Fighter, East Side kid
• Wally Kurth as Agent Six, Captain Calan, Maxwell, Systems Op
• John DiMaggio as Bobo Haha, Skalamander, Architect, Jungle Cat, Pete Volkov, Robo Bobo Haha, Michael, Hunter Cain (2nd time), Dark figure, Rath, Providence Agent (1st time), Huckster, Vostok, Pyreptryx, Nyquist, Biruta, Umpire, Infected 2, Human EVO, Lunk, Waiter (1st time), Payson, Bug, DJ, Older Providence worker, Dock Worker, Guard 1, Providence Tech (2nd time), Villager, Providence Soldier 1 (2nd time), Black Pawn
• Grey DeLisle as Rebecca Holiday, ZAG-RS, Little Girl (Slug EVO), Woman (Rock & Mud EVO), Female Co-pilot, Doctor Rhodes, Diane Farrah, Isabella, Violeta Salazar, Little Spanish boy, Reporter, Kate, Larvus, Wade, Waitress, House wife, Trig Student 2, Beach Girl 1, Echoey Voice 2, Computer, Innocent girl, News Reporter, Librarian, Lady
• J.K. Simmons as White Knight, Cured E.V.O., Waiter (2nd time), Control Voice
• Fred Savage as Noah Nixon, Beagle (1st time), Waylan, Infected 1, Sit-Ops Tech, Team leader
• Troy Baker as Van Kleiss, Biowulf, Agent Weaver, Roswell, Captured zombie, Businessman, Etude, Echoey Voice 1, United Nations Official, Providence Tech (2nd time), Guard, Male Party-Goer, Providence Soldier 1 (1st time)

Recurring characters

Home video

Warner Home Video released Volume 1 DVD, a two-disc set that contains the first nine episodes of the series on October 19, 2010.^[9]

Video game

A video game, entitled Generator Rex: Agent of Providence, has been developed for Wii, PlayStation 3, Nintendo DS, Nintendo 3DS and Xbox 360. The game was released on November 1, 2011, in the United States, developed by Virtuos and published by Activision.^[10][11] The plot involves Van Kleiss attempting to find blueprints to build an Omega-One Nanite. The entire voice cast reprises their roles from the series. Agent of Providence was given an E10+ rating by ESRB.^[12] The game was also scored by the series' composer, Kevin Manthei.^[13]

Toy line

Mattel has produced a toy line based on the series. For the main figures each is approximately 4 inches tall and packaged with an ordinary day E.V.O. There were also deluxe figures, EVO attack packs, as well as other waves and lines that were never released including a line from MEGA Bloks was announced (in 2010) featuring construction sets.^[14]

Publications

Cartoon Network has featured Generator Rex and Ben 10 in their and DC Comics's Cartoon Network: Action Pack comic books.^[15] Two 3D picture books (featuring cardboard 3D glasses) "EVOs and Heroes," a whole analysis on characters and their abilities and "The Swarm," an adaption of the episode of the same name, where Rex must fight insect E.V.O.s that feed on metal, have also been released.^[15] For beginning readers, the story "Leader of the Pack" is also based on an episode and features Rex and Bobo being captured and locked in an underground prison cell.^[15]

In February 2013, IDW Publishing announced a partnership with Cartoon Network to produce comic books and issues based on its properties. Generator Rex along with Ben 10 was one of the titles announced to be published.^[16]