As a teen, he is voiced by Yuko Sanpei in the Japanese version of the anime, and by Johnny Yong Bosch in the english version of the anime.
As an adult, he is voiced by Keiji Fujiwara in the Japanese version of the anime, and by Johnny Yong Bosch in the english version of the anime.
Renton Thurston is a teenage boy, who wears a jacket with long sleeves,short pants, and a running shoes. In the series finale, "Wish Upon a Star", Renton dons a new outfit consisting of a red-and-white hoodie with the entire center of the hood while the hood itself is white and its sleeves are both a mixture of red and white. He also wears dark shorts, white socks and black boots.
In Eureka Seven: AO, at the age of 30, Renton has grown at about six feet and is much leaner. His face has leveled out and his voice has deepened. The front set of his brown hair has turned white, which remains unexplained. He wears a dark jacket with large black buttons which implies his occupation with the military, a black turtle neck that is worn underneath his jacket, dark pants, black gloves that come up to his elbows, and black boats that come to nearly his knees. In addition, he wears a replica of Eureka's necklace around his neck, which he had supposedly used to pilot the Nirvash Mark I. As a result of him having to grow up quickly at an early age, Renton is more serious and calm that he was in Eureka Seven, but he still puts the lives of his loved ones before his own.
At the start of the series, Renton was a despicable boy who allows himself to be bullied by other young teenage school boys. After meeting Eureka, he became incredibly shy around her, although he became less shy after coming to understand her flaws and developing a personal desire to protect her. Despite this, he was still ignorant on whether or not his actions benefit or hurt her, no matter how good his intentions are. His realization to face his responsibilities and keep his word gave him the courage to do what is needed. Due to the impact of the war, seeing how the lives of everyone around him are affected, and understanding how everyone depends on him due to being the chosen one to stop the war between the Scub Coral and humans, he gradually became more brave, mature, and confident in himself.
During season 2, in midst of his rift with Eureka and the Gekko crew, he falls into a depression, due to his belief that he is resented by everyone. Initially, he tried to make his feelings clear to them, but after they ignored or rejected him, he concluded that he never belonged on the Gekko and was never wanted in the first place. This action also steams from the pressure of trying to help Eureka and the pressure to fight the way the crew does (although he was horrified when he finds out that he has unknowingly killed many people in battles and he had a mental breakdown). During the time he was away, he was able to sort out his confused emotions and try to figure out what the purpose of his existence is. With Eureka "rejecting" him and everyone else "abandoning" him, Renton felt alone and unwanted. His time with Charles and Ray helped him realize that he is simply a kid who often lets his emotions take control him and leave him little time to really think of the consequences of his actions. Charles' words of keeping his word enables him to finally believe in himself and he begins to mature into the young hero he wants to be. The deaths of Charles and Ray had haunted him until he began his relationship with Eureka. The deaths of the Beams had a particular effect on him, making him very guilt-ridden for unintentionally leading them to invade the Gekko and not doing anything to prevent their deaths.
However, he can also be a person with strong resolve who is willing to do anything to accomplish something that is important to him without hesitation. When Renton learned the truth behind the current war and how Eureka required a partner to stop it and he was the chosen partner, Renton was willing to put the abuse he endured from Holland and the ill feelings he harbored towards the crew aside in order to fulfill his newfound responsibility.
In adulthood, Renton became matter-of-fact, calm and serious, evident in his mature and blunt expression when he first appears in Eureka Seven: AO. Renton also developed a strong sense of duty, becoming more like Holland, which included the tendency to make difficult, often illogical, decisions for the sake of his duties. However, he becomes obsessed with destroying the Scub Coral following the death of his daughter and often rejected any other resolution that involved protecting his son and maintaining peace with the Scub Coral altogether; he blamed the Scub Coral for Amber's death and saw it as a threat to Ao's life. He was willing to do whatever it took to protect his son even if it meant sacrificing his relationship with Eureka (who consented to this, as she too was desperate to keep Ao safe). Becoming a father had a major impact on Renton, as it is obvious that Ao and Amber are the most important people, next to Eureka, in his life, and not being able to have the happy family he so desperately wanted with Eureka left him a broken man. When Ao opposed his plan to use the Quartz Gun to erase the Scub Coral, Renton understood that Ao didn't want to put the lives of Eureka and others in jeopardy but, as much as he loved Eureka, he was unwilling to lose his son for the sake of others. Renton becomes somewhat prideful due to not even apologizing to Ao for trying to seriously beat him in battle. However, Renton still loves his son enough to risk his own life to protect him. He also acknowledges his mistakes and is willing to atone for them if it will make Ao happy. This is seen when Ao told his parents that he didn't want them to make any more sacrifices for his sake, and Renton agreed to stop with his efforts of destroying the Scub Coral and granted Ao's request to let him deal with the Secrets alone while he and Eureka returned to their world because he trusted his son to do the right thing, proving himself as a loving father and husband.
- From the first episode, Renton made it clear that he hated his father, Adroc, because he believed Adroc abandoned the family for his research, and felt no sympathy for the man despite him being "dead". However, when Eureka told Renton that Adroc released the Amita drive to protect his family, Renton was able to forgive his father and even expressed his feelings with no malice to him when they finally met in the Scub Command Center. They work together.
- Although he is initially presented as an immature teenager, Renton is revealed to actually be a genius; seen with his skills in mechanical engineering, his ability to pilot Nirvash, and when he invents the first IFO by combining his knowledge of the Scub Coral and LFOs.
- In the manga, Renton designed the Nirvash TypeZERO spec 2 form from parts, which earned him recognition as a mechanic almost as great as his grandfather.
- Renton joined the Gekkostate for three reasons: to lift as much as possible, to be near Holland, and to be together with Eureka. However, his reasons become that to protect Eureka and end the war between the humans and Coralians.
- In Eureka Seven: AO, the front set of his brown hair is white; why this happened is never explained.
- His son, Ao, inherited all of Renton's facial features while having Eureka's eye and skin color. Ao's hair was originally brown like Renton's, but it turned turquoise when he first came into contact with the Nirvash. He is also as blunt as Renton is, according to Eureka.
- Although he doesn't want to be involved with violence and use guns, Renton is willing to fight in order to protect his loved ones, and has used a gun without firing one about three times in Eureka Seven and carries around the rifle that had previously belonged to Charles in Eureka Seven: AO.
- It is revealed in episode 50 (according to the family record book) that Renton married Eureka and adopted the children on April 2, 12006.
- Episode 50 also revealed that his date of birth is February 28, 11090.
- His zodiac sign is Pisces.
- Episode 50 also revealed that his date of birth is February 28, 11090.
- In total, Renton has five children with Eureka: three sons and two daughters. At 16, he adopts Maurice, Maeter and Linck, and has always treated them as his own children. Shortly after, Eureka gives birth to his biological children, Amber and Ao.
- It is thought that Renton's name is inspired by Mark Renton, a character from the film Trainspotting and his surname, Thurston, is a reference to Thurston Moore of the band Sonic Youth.
- How Renton resented his father, Adroc, for supposedly abandoning the family for his research is similar to how his own son, Ao, resents him due to Ao's initial belief that Renton abandoned him and Eureka. However, Renton later discovered that his father sacrificed himself to save his family and the planet from the First Summer of Love. Also, Ao discovered that Renton always loved him and Eureka, and sacrificed his own happiness and was trying to destroy the Scub Coral in order to save his son due to the guilt he feels for failing to save his late daughter.
- In the first novel, Blue Monday, it is noted that Renton is the third shortest boy in his school and he had dated one classmate, but never had a romantic interest in girls until he met Eureka.
- Despite rejecting his grandfather's attempts to force him to become a mechanic, Renton always intended to be a mechanic and actually enjoys it. Also, even though he wanted nothing to do with the military, he ended up working for the military as a scientist due to his work in creating the RA272 Nirvash and his involvement in conducting research on the disappearance of the Scub Coral.
- In Eureka Seven: AO, Eureka told Ao that his Quartz Gun is the weapon Renton has been searching for a long time in order to save them, but how he has knowledge of the gun, which originates from Ao's world and wasn't in Ao's possession during her first appearance, is unknown.
- Keiji Fujiwara (his voice actor as an adult) also voiced Holland Novak.