Damron was a Xindi-Reptilian scientist, placed in charge of developing a bio-weapon with which to destroy Humanity in the 22nd century.
In 2153, when the Xindi Council disallowed the development of a bio-weapon in favor of a larger, more powerful version of the initial probe they sent to attack Earth, the Sphere-Builders, attempting to increase their chances of successfully destroying Humanity, sent Damron and his team back in time to Earth, the year 2004, where they could work on the bio-weapon in secret from the rest of the council. Damron enlisted the assistance of an unscrupulous blood bank employee named Loomis to supply him with victims of each blood type, which would allow them to modify the virus they were developing to target all Humans. After three months on Earth, their activities were detected by the 31st century temporal agents, who sent Daniels to inform Captain Archer of Damron's activities. Providing him with a temporal beacon and temporal tags with which to mark anything which did not belong in that time period for retrieval, Daniels sent Archer and T'Pol back in time on a mission to stop Damron.
While on Earth, Archer and T'Pol were able to locate the secret location out of which Damron and his team were operating. Destroying their operation and killing Damron's team, they forced him to flee with the canister of the virus. Confronting Damron on a nearby rooftop, Archer demanded to know the nature of the bio-weapon. Damron, however, refused to provide Archer with answers, and attempted to release the virus, forcing Archer to kill him. (ENT: "Carpenter Street")
The bodies of Damron and his team were subsequently stored in Enterprise NX-01's morgue. The bodies, along with the bio-reactor they were using to synthesize the virus, were used by Archer in an attempt to convince Degra that the Sphere-Builders were attempting to manipulate the Xindi. (ENT: "The Forgotten")
In "Carpenter Street", Damron was played by Jeffrey Dean Morgan. Damron's dead body, seen in "The Forgotten", was portrayed by regular background actor Henry Farnam.
In a 2012 interview with Entertainment Weekly, Jeffrey Dean Morgan stated that he only took the role of Damron because he needed some money to pay his bills. He recalled the experience of playing a Xindi-Reptilian was not pleasant for him at all, remembering that he had to stick straws in his nose to breathe, was claustrophobic the entire time, and that he couldn't eat. He remembered going to his home in tears and claimed he nearly quit acting because of his experience on Star Trek: Enterprise. (Entertainment Weekly, issue #1201, p. 65)