As a child, Rex was born into a poor family. Relief came eventually in the form of a government agent. The man offered his family a life of luxury in exchange for Rex. The deal was made and Rex was taken. Rex was made into a soldier. he was trained in gymnastics and fighting and was put through experiments to alter his body including giving him increased strength and the ability to charge inorganic materials. He was used as an agent and was sent to places as a terrorists of sorts. All seemed fine until one day he decided to escape. It might have been a longing to meet his true family and that's exactly what he did as soon as he was clear. He found his family prosperous with young girls. This devastated him and he became secluded. Eventually he met up with Robot and formed the Teen Team.
Rex was created by Robert Kirkman, his first appearance was in Invincible #2.
An Invincible Ally
Rex-Splode was one of the first heroes Invincible met along with the rest of the Teen Team during a fight with the Mauler Twins. Invincible thought he was a jerk and had a hard time getting along with him especially because they both had feelings for teammate, Atom Eve, whom Rex was with. Their relationship was short lived however when Eve found Rex with fellow teammate Dupli-Kate. This angered Invincible, but eventually they became friends
When the original Guardians of the Globe were killed, Rex decided to try to get into the team. When he was at the member drive he got in a fight with future teammate Monster Girl because of her appearance. With Robot as team leader Rex was granted membership as long as he behaves. He coasted with the team and enjoyed his relationship until one day he came into HQ and found Dupli-Kate with The Immortal much in the same way Eve found her and Rex. During one of the team meetings Cecil revealed the real Robot, a young boy who looked remarkably similar to Rex. Robot explained that his body was not sufficient so he made a younger clone of Rex as a replacement body.
During the Sequid's attack on Earth, Rex, Shrinking Ray, and Kate were all benched because they could be used as hosts for the Sequids. However, during the rest of the team's time in space the Lizard League attacked a nuclear missile base. The remaining team went to confront the league and appeared to have the upper hand by killing Salamander and Iguana, but the strongest member, Komodo Dragon, turned the table by killing Shrinking Ray and apparently Dupli-Kate and all her clones. Rex sacrificed his hand to put an explosive in his head, killing him. Rex thought he won until King Lizard pulled a gun on him. Rex fought it out and ended up getting shot in the head. Luckily King Lizard passed out when he did and Brit showed up to take them away. Rex was able to heal and got a robotic, replacement hand that shot explosive projectiles.
These events seemed to have matured Rex emotionally. He takes his activities as a superhero more seriously. Upon hearing of Invincible and Atom Eve's new relationship, Rex sincerely wishes them well, much to Eve's surprise. After Invincible leaves the government, Rex along with Robot, Monster Girl, and Bulletproof leave the Guardians of the Globe to reform the Teen Team.
In order to save his team from an Invincible from an alternate universe, Rex blows himself up so they have time to escape, destroying himself and the Invincible.
Rex-Splode has the ability to alter the chemical makeup of inorganic materials, causing them to become unstable and explode. He has limited invulnerability and slightly enhanced strength. After his hand was bitten off by a member of the Lizard League, Rex received an artificial hand that can fire exploding projectiles.
During Invincible's fight with Angstrom Levy, he met a group of possible future Guardians of the Globe who had searched for him for fifteen years. This team's Robot turned out to be Rex wearing a suit much like the one the Robot clone wore during the Sequid battle.
Another alternate version of Rex-Splode went by the name Hex Splode, he part of Emperor's Elite.
In Other Media
Rex will appear in the series, voiced by Jason Mantzoukas.