TV-Series
Description
Racer X, also known as the Masked Racer, is a recurring character in the anime Speed Racer. His true identity is Rex Racer, the eldest son of Mom and Pops Racer and the older brother of Speed and Spritle. The name Racer X is a play on his own first name, combining Rex with the idea of Racer EX. He drives the number 9 car, the Shooting Star, a yellow racing machine noted for its agility and high-tech features.

Years before the events of the series, Rex wanted to compete as a professional driver, though Pops warned him that he was not yet ready. During his first major race, Rex was leading with less than one lap remaining when he lost control and wrecked the Mach One, the first car Pops had ever built. Pops angrily berated him for the crash, and Rex responded by fleeing home and exiling himself, vowing to become the greatest race car driver in the world. During this exile, he assumed the masked identity of Racer X to pursue his racing career.

In personality, Racer X is described as heroic, mysterious, flamboyant, selfless, sympathetic, and often brooding. He operates as a soldier of fortune and international agent, using his racing career as cover for secret work. In several stories he works to thwart criminal and corporate schemes and sometimes cooperates with Inspector Detector, though it is not made clear whether he belongs to the same organization. In his agent persona, he is often shown wearing a white linen suit, a Panama hat, and wraparound sunglasses.

His motivations are rooted in his estrangement from his family and his desire to prove himself as a driver, as well as his commitment to fighting crime. Because of his secret work, he cannot reveal his true identity to his family, but he remains deeply loyal to them. He repeatedly sacrifices winning races to protect Speed from drivers and others who try to harm him, and his assistance nearly always results in Speed winning while Racer X finishes second. He then leaves the scene unnoticed, receding into his secret life.

In the story, Racer X serves as both a rival and a guardian to Speed. Speed begins to suspect that Racer X is his estranged older brother during the two-part Challenge of the Masked Racer storyline. Pops and Speed both acknowledge that Racer X is the superior driver of the two and the greatest driver they have ever seen, yet Speed remains determined to defeat him. Near the end of the series, in the episode The Trick Race, Speed finally gets the chance to directly ask Racer X if he is his brother, but he is knocked out before he can receive an answer. Afterward, Racer X confesses to Captain Terror that he is truly Rex. He then vows to quit automobile racing and become a full-time international secret agent. As he leaves, he takes off his mask and leaves it beside the unconscious Speed, telling him that he will look after him wherever he goes. When Speed wakes and finds the mask, he is finally convinced that Racer X is his older brother.

Notable abilities include his exceptional driving skill, which places him above even Speed as a competitor, and his expertise in undercover work as a secret agent. He is also physically formidable and has received training in combat and other agent skills in some versions of his story, along with instruction from figures such as Prince Kabala before taking on the Racer X identity. His combination of racing talent, selflessness, and hidden loyalty defines him as a protective presence who watches over his younger brother from the shadows.