His brother, Roman, entrusted Rex with the mission to use the Signers to someday stop him, as Roman became a Dark Signer. Rex uses his influences to gather the Signers and assist them, but secretly used them in order to become a Dark Signer and absorb the powers of a Signer.
The word "Rex" is Latin for "King". This demonstrates his influence and power in both New Domino City and Satellite.
Rex and his brother Roman, served as assistants to the developer, Dr. Fudo of the Enerdy technology. Roman and Rex, while working for R.R.D. Added by Rex Godwin, Roman is made lead developer after Dr. Fudo attempts to abort the project as its too dangerous. Dr. Fudo managed to pass on three of the four control units; the cards "Red Dragon Archfiend", "Stardust Dragon" and "Black Rose Dragon", to Rex after being shot at for taking them. He begs Rex to stop the Enerdy project.
Rex goes to find Roman and finds him in a lab, having just amputated his arm. Roman hands Rex a container with the arm and tells Rex to do what it takes to defeat him after the Signers appear. He orders Rex to leave and hits a self destruct button, resulting in the Zero Reverse, so that he may be reborn as a Dark Signer.
In order to make sure that the Dragon cards fell into the possession of their corresponding Signers, Goodwin released them to the public.
Rex constructed a Duel Runner and moved to a coastal part of Satellite. Nobody knew or found out who he was at the time. Every day he used to stare across the waters dividing Satellite and New Domino. One day he began constructing a bridge to the city.
Initially people thought he was crazy, but came to help him after a while, seeing his progress and determination. Some people frowned at the idea and forced construction to halt. Rex became wanted by Sector Security and his helpers abandoned the project.
Rex ended up cornered by Security one day. Rather than be caught and spend the rest of his life in jail, he rode his Duel Runner along the bridge and flew off to the other end of the sea. This act caused Goodwin to lose his left arm.
Most people never knew what became of him and yet regarded him as a legend. The incomplete bridge was later named Daedalus Bridge.
Goodwin managed to survive the ordeal and later replaced his arm with a mechanical one.
Director of Security
Goodwin managed to make his way to becoming director of New Domino City and Sector Security, as well as leader of the secret organization known as Yliaster, with Lazar as his all purpose assistant.
Knowing the Dark Signers will return to wage war against the Signers, Goodwin isolates the Satellite from New Domino. Since the original Enerdy Reactor, located in Satellite, is the gateway to the underworld, Satellite is to become the battlefield. Goodwin cleanses New Domino, by sending any criminals or socially inadequate people to Satellite, making New Domino a utopia, while Satellite is flooded with people considered "scum" by many. Goodwin masquerades his beliefs of class and plutocracy with utilitarianism, saying that everyone must work together to maintain the delicate balance between Satellite and New Domino City.
Goodwin continues Enerdy research in New Domino and uses it to power the city. Zigzix leads the project, but must operate under Goodwin's instructions.
Using his influences within the city, Goodwin began to locate the Signers.
He finds the Satellite resident, Jack Atlas, who has a Mark of the Dragon, identifying him as a Signer. Goodwin organizes an escape plan for Jack, promising him that he will live as a Duel King in New Domino. Jack complies, although it meant turning his back on and stealing from his friends. Jack apparently becomes Goodwin's protegé, but is really used for publicity and a tool in Goodwin's plans.
After witnessing the appearance of the Crimson Dragon during Yusei's and Jack's Turbo Duel, he reveals his status to Jack as the 360th Star Guardian and informs Jack that he is a prophetical savior called a "Signer". However, Goodwin conceals the whole truth from Jack. Goodwin believes the truth would spark Jack's fire.
Goodwin later arranges the Fortune Cup, in hopes of finding Signers by inviting participants randomly and inserting his own dueling assassins who will expose a Signer upon dueling one. Goodwin is shown to have control, either directly or through Zigzix and Lazar, of nearly every aspect of the tournament. He also has a large string of backup plans should things not go his way: for example, upon discovering that Leo had substituted for his Signer sister in the tournament, he arranges a "consolation Duel" to expose Luna.
Rex catches the spike, revealing his mechanical arm. Deltaneos Greiger, whose hometown had been destroyed, was been promised reconstruction aid to his hometown depending on how he preformed in the Fortune Cup. Greiger gets misinformed that Goodwin was responsible for the village's destruction and after he loses to Yusei, he attacks Goodwin, resulting in a spike from his Duel Runner flying off and Goodwin catching it, revealing he has a mechanical left arm to Lazar and Jack.
During the Fortune Cup final, while the other four Signers are in the premises, he uses Roman's old arm with the fifth Mark of the Dragon to Summon the Crimson Dragon. (In the English anime, he refers to himself as the fifth Signer). He is unconcerned when Jack loses to Yusei in the final round. Due to the appearance of the Crimson Dragon during the Duel, the public and media couldn't see how the Duel ended. When the media questions him about it, stating that the public isn't satisfied by the outcome of the Duel, he is able to avoid telling the truth.
Dark Signers return
Goodwin appears at the premiere of the film Atlas Rising. After assisting at opening event and talking to the people, he tries to leave but is stopped by Angela Rains, who publicly questions him about Jack being from Satellite.
Goodwin and Lazar meet Yusei on a bridge to tell the boy "the truth". Goodwin tells Yusei about the 5000 year old battle between the Signers and Dark Signers, how the Earthbound Immortals got sealed in the Nazca Lines and how the Crimson Dragon divided itself into five parts, each sealed in a Mark of the Dragon. When Yusei asks him why the battle has began again Rex tells him about the Zero Reverse and how it unleashed negative energy, which was also emitted from the Nazca Lines and now the Dark Signers plan to use the same Enerdy reactor from the Zero Reverse incident to open the door to the Underworld. In order to stop this, the Signers must defeat the Dark Signers.
Yusei insists on evacuating Satellite before this happens. Goodwin refuses as the people in New Domino will become victims instead. Yusei angrily figures out that this is why Goodwin isolated Satellite. Goodwin tells Yusei he must combine his powers with the other Signers in order to stop the Dark Signers. After Yusei asks who the fifth Signer is, Goodwin says that he is destined to appear eventually. Goodwin arranges for Yusei to be airdropped into Satellite.
Goodwin watches the Duel between Yusei and Kalin.
After Carly Carmine becomes a Dark Signer, Lazar and Goodwin become aware of her presence and watch her duel Sayer on a screen, in which they see the Hummingbird geoglyph appear in the city. They also see Misty Tredwell Duel around the same time and place and observe her Lizard geoglyph appear.
Rex later invites the Signers to his house to give them more information concerning the Signers and Dark Signers. He tells the Signers how they have been brought together by fate, more about the Dark Signer's powers and their use of the Earthbound Immortals. Reluctantly he tells them that a Dark Signer cannot return to their normal self as they are no longer of this world.
After the black fog incident in Satellite, Goodwin arranges for the Signers to return to Satellite to fulfill their mission. Before the Signers leave Yusei asks Goodwin to promise to finish Daedalus Bridge, once the Dark Signers threat has been eliminated, which Goodwin accepts.
As a Dark Signer
Goodwin meets-up with Roman and engages in a Duel, using his Duel Disk, which folds out of his mechanical arm. Rex loses on purpose, so that he may be reborn as a Dark Signer. He tells Roman that he knows Roman cannot defeat Yusei and if the Dark Signers lose the battle, then another battle would occur in the next thousand years. He dies in his brother's arms. In his last words (before being reborn as a Dark Signer) he tells his brother that he intends to stop the chain of fate by destroying the world using the King of the Underworld's power and rebuilding it using the Crimson Dragon's power.
After a while Crow Hogan finds him in an old room. Rex informs Crow a little about the past before cutting him off by turning towards a sliding door. Later Rex returns back to New Domino City and back to the Sky Temple to collect Roman's arm. Later after Akiza fails to seal the final tower before sundown, the Condor Geoglyph appears on the sky. Then the Crimson Dragon appears once again and guides the Signers to Rex Goodwin. As he reveals to them that he has acquired the powers of both Signer and Dark Signer, as Goodwin intends to use the power of the Crimson Dragon along with those of the Wicked God in order to become the Ultimate God. As the Condor mark on his back shows itself, he then removed Roman's preserved arm from the canister and attached it to himself and then declares that a Shadow Turbo Duel will be held within Condor Geoglyph as a ritual to welcome the King of the Underworld.
Yusei, Jack, and Crow accept the Duel in order to stop the resurrection of the Underworld Ruler. During the Duel he reveals to them about how and why he became a Dark Signer. Shortly after the Duel begins, Goodwin summons forth all the birthmarks together to form the Mark of the Dragon on his chest. He also reveals that he was the stranger from the Daedalus Bridge legend.
Roman and Rex before passing on to the afterlife. Ultimately, Rex loses to Yusei with his Earthbound Immortal destroyed by "Majestic Star Dragon" and the King of the underworld destroyed by the Crimson Dragon. With their defeat the Dark Signers were revived as their old selves, but Rex and Roman remained absent. They agree that since they became Dark Signers by choice, they should get no second chance.
Rex is the last Dark Signer to fall.
Sometime after the final battle, the Daedalus Bridge is completed as a far more modern bridge.
Even After Goodwin's defeat, his presence is still felt throughout some parts in the new season, As it was shown in Dragan's First duel against Jack, prior to the main story's plot, Godwin had forced Dragan to lose on purpose so as to protect Jack Atlas' reputation as King, he was also mentioned by Placado earlier when the season first started about his attempts to harness the power of the crimson dragon to change the destiny of the world, a plan which was in some way similar to Yiliaster's own attempt to change the future, minus the usage of the crimson dragon.