- "Organics are no match for the mechanized might of the Haydonites."
- - unidentified Haydonite to Scott Bernard.
This species were known to be an ancient species within the Local Group who lived on the artificial world of Haydon IV. They were seemingly named after the mysterious enigmatic entity known as Haydon who had influenced the many planets within the Local Group and was responsible for creating the Awareness that controlled Haydon IV. Since that time, the mechanical Haydonites lived a peaceful existence where they were protected by the powerful defense systems of their homeworld. Their remarkable defensive systems meant that the rise of the Tirolian Empire did not threaten them even when the Robotech Masters began conquering the other worlds in the Local Group through their mastery of Robotechnology. At some point, the Robotech Master Zor arrived on Haydon IV and visited the Haydonites where he met with the Awareness to answer some questions before departing. In addition, the Tirolians established an embassy in the capital city of Glike. Prime Administrator Vowad served as the leader of the Haydonites in this time with the majority seeking to not intervene in the affairs of other races. The reign changed when their supply of Protoculture was lost with the Protoculture Matrix onboard the SDF-1. By this era, the Invid had been transformed into a war-like race due to the actions of the Robotech Masters and began conquering their empire. Similar to the Robotech Masters, the Invid were unable to conquer Haydon IV due to its defense systems that targeted anyone using weapons but instead occupied the world without violence.
The Haydonites did not respond to the Invid and even served them when they were on their world. This action sparked some dissension among certain Haydonites such as Veidt and Sarna who believed that peaceful neutrality was a futile gesture when facing the threat of the Invid which was a stance the majority of their kind did not share. With the Tirolian Empire nearly conquered, the Regent dispatched his scientist Tesla to gather specimens from the Local Group for experiments for the Regess which included both Sarna along with her mate Veidt. During this time, their prison ship the Farrago was overthrown by the slaves who took it over and formed a loose alliance known as the Sentinels who sought to free their homeworlds. This band arrived on Tirol where Veidt used his diplomatic abilities to speak to the Humans of the Robotech Expeditionary Force. The two sides formed an alliance with Rick Hunter and Lisa Hunter accompanying them on their mission to liberate their planets. Their campaigns saw the worlds of Karbarra and Garuda liberated though the latter mission saw several of the Sentinels poisoned by the toxic atmosphere of the Garudan homeworld. Thus, Veidt suggested that they use the advanced medical knowledge of the Haydonites to heal them but his people's homeworld was now occupied by the Regent's army. The two sides met in a diplomatic exchange where they agreed to hand over Tesla in exchange for Rem along with the medical treatments.
During this time, Sarna attempted to convince her father Vowad to change the Haydonite stance on neutrality to which he refused. However, Janice Em interfaced with the Awareness and altered its defense system programming to ignore the Sentinels. This combined with a rebellion amongst the Praxians in the slave pens led to the Invid forces struggling to contain the situation. Invid forces became victims of the defensive system that ignored the Sentinels and attacked the Invid whenever they attacked or retaliated. The death of Sarna also saw Vowad turn against the Regent and he manifested his grief in the planetary defense system that took the form of Zor that destroyed the Invid armies along with the land carrier thus forcing their retreat. A funeral was held for Sarna whilst the Haydonites dedicated their help to the Sentinels and REF. As such, they provided new advanced extendable armor systems for the Sentinels and a starship in the form of the Ark Angel that was dispatched with Veidt providing assistance to Rick Hunter as it was launched. The ship was later attacked by the Black Death Destroyers but managed to escape for a mission to liberate Spheris.
- The comic series ended with Book Four and thus the future activities of the Haydonites is unknown.
- "This means nothing! All those that embrace Protoculture are doomed! We... shall... prevail!" - unidentified Haydonite to Captain Grant.
Within the new continuity, the Haydonites were a mysterious race that were the developers of Shadow technology. They were known to had feared the power of Protoculture and became bitter enemies of the Invid who referred to them as the Children of the Shadow. This feud saw the Haydonites devastate the original Invid Homeworld with powerful weapons with such a fate given to any race that used Protoculture. Despite their efforts, the Invid managed to survive the attack and departed until their Flower of Life was stolen from them by the Robotech Masters leading to a war against the Local Group. According to Janice, the Haydonites were said to have suffered at the hands of the Invid. In this time, the Haydonites seemingly joined the Sentinels in order to combat the Invid invasion and became allies fo the REF. They decided to provide their Shadow technology to the REF along with other advanced technology to combat the Invid such as Shadow Devices, Synchro cannons and aided in the analysis of the mysterious Neutron-S missiles. Many of these advancements of the REF were unknown to the common soldiers as the Haydonites wanted to maintain their privacy. Thus, all their technical data and knowledge was actually passed through Janice who was made with a mixture of Human and Haydonite technology. Unknown to anyone, the Haydonites were following the direction of the Awareness and urged the REF in the conflict against the Invid to accomplish their own goals, the primary of which was the destruction of Protoculture and all who used it. What end this would serve is unknown.
The Haydonites watched with keen interest at the conclusion of the Third Robotech War when the REF sought to free Earth from the control of the Regess. They intended for the Humans to deploy the Neutron-S missiles that would have destroyed the Earth and the entire REF if used. A test firing conducted by the SDF-3, which held the Protoculture Matrix, created a black hole as a result. In order to prevent this knowledge from being sent to the REF, a Haydonite ship attempted to silence Rick Hunter's flagship, but they failed in preventing the Icarus from saving the Deukalion and fleeing. Shortly thereafter the SDF-3 vanished, but the Haydonites were confident it survived the attack, much to their dismay.
When the Regess escaped with the Invid, destroying the Neutron-S Missiles as she went, the Awareness provided new instructions to the Haydonites, telling them to conduct more direct action in the extermination of the "Protoculture addicts". With the Invid now beyond their grasp, the Haydonites were fully focused on the destruction of humanity, and they assembled a fleet for an assault at Space Station Liberty. When they arrived, they used their Shadow Technology's hidden traps to cripple and devastate the REF's remaining forces, igniting the Fourth Robotech War. They were prepared to destroy the station as well when they learned that Janice was aboard. Feeling that she was too valuable, they decided to board, and either extract her to learn the location of the Protoculture Matrix if she knew it or eliminate her to prevent their enemies from gaining a tactical advantage. The infiltration force attacked Space Station Liberty where they were defeated by Lieutenant Commander Scott Bernard and Captain Vince Grant who detonated the station's Neutron-S missiles and seemingly destroyed the Haydonite invasion fleet.
Despite this apparent defeat, the REF were confident they would meet the Haydonites again, and redoubled their efforts to locate the SDF-3 before the enemy. The ultimate goals of the Haydonites remain unknown.
According to Robotech: World Killers, the Haydonites do not reproduce but rather create their offspring as a form of art. These young incorporate the characteristics of their elders and selected innovations.