Sean Barker is the main protagonist in the live-action Guyver films based on the Japanese manga and anime. In this Americanised version of the Guyver story, Sean fulfills the role that Sho Fukamachi served in the original, donning the symbiotic Guyver suit and battling against the evil Chronos Corporation and their mutant killing machines known as Zoanoids.
In the first Guyver film, Sean is portrayed by Jack Armstrong. In the sequel Guyver: Dark Hero, he is portrayed by David Hayter. Like Sho in the comics and anime, Sean is killed in battle by Zoanoids but is restored to life by the Guyver's control medal, which reconstructs his body from only a small fragment of his genetic material.
Sean Barker is a normal young man trying to get by in the big city of Los Angeles, spending his free time taking martial arts lessons and pining over the affections of his Japanese girlfriend Mizky Segawa. His life is turned upside down after he overhears Mizky talking with a detective called Max Reed after karate practise and finds out that Mizky's father has been murdered after he had stolen an unknown device from his employers, the Chronos Corporation. After spying on the police investigation of the crime scene, Sean accidentally discovers a mysterious object in the dump. He takes it from the dump, but on his way home he is assaulted by a group of street punks. Whilst fighting the punks, Sean unwittingly activates the strange device that he found and it merges with him, turning him into the Guyver. With the Guyver's strength, he easily beats up the hoodlums.
The following night, Sean visits Mizky's apartment only to find that the place has been ransacked. Seeing two strange men carrying a rolled-up carpet as he arrived, he rushes back outside and finds that these men and their associates are attempting to kidnap Mizky. The detective Max Reed is also on the scene and he and Sean try to rescue Mizky, prompting the strange men to transform into horrible monsters. The creatures attack and Sean transforms into the Guyver. He manages to kill one of the Zoanoids but the others discover his weak spot: the metallic orb in his forehead. Lisker manages to beat the Guyver to the floor and then rips out his control medal, causing the bio-boosted armour to overload and disintegrate, and Sean along with it.
After Sean's apparent death, Lisker and the Zoanoids return to Chronos with the Guyver's control medal. Whilst being studied in the Chronos lab, the control medal analyzes the data it recorded from its host's brain and recomposes Sean's body from the DNA left on its fibers. Sean is restored to life and uses the power of the Guyver to defeat Chronos' director Fulton Balcus and rescue Mizky.