Haydon IV (sometimes identified as Haydon V) is the homeworld of the highly advanced cybernetic race known as the Haydonites.
An artificial world located within the Local Group which was one of the many that were influenced by the mysterious being known as Haydon. It was said to had been created to house an artificial intelligence known as the Awareness and was populated by mechanical beings known as Haydonites who worshipped Haydon as a creator being. The surface also housed one of the statues that represented Haydon similar to the one located on Karbarra. Haydon IV contained highly advanced technology including sophisticated medical systems along with a powerful defensive energy weapon that targeted any weapons and destroyed them which could either be starships or personal hand-held weapons. The capital of the planet was known as Glike and contained a large sea of water underground. After the Great Transition era, the Tirolians were known to had established an embassy on Haydon IV. When Zor rebelled against the Robotech Masters, he seeded Haydon IV with mutated seeds of the Flower of Life which attracted the attention of the Invid.
After the conquest of the Tirolian Empire, attempts were made to conquer Haydon IV but it was eventually discovered that passive occupation of the planet was possible which allowed the Invid to take control of the world without showing any hostile action. Prime Administrator Vowad was known to had even assisted the Regess in gathering information whilst the Invid occupied the Imperial Spires and an Hive was situated outside the capital city. These actions caused some Haydonites to question their position on neutrality which saw Veidt along with Sarna joining the alien alliance of races known as the Sentinels. After the destruction of Praxis due to the Genesis Pit experiments, the Regess relocated the entire Praxian race to Haydon IV where she consulted the Awareness to find the location of the Protoculture Matrix. Following this point, she departed the known worlds to find the planet Earth with her half of the Invid and left the Regent behind to battle the Sentinels along with the Robotech Expeditionary Force.
During the liberation of Garuda, the Regent occupied Haydon IV and the Sentinels moved to the planet with the joint purpose of liberating it as well as find a cure for the Garudan toxic atmosphere which had afflicted Rick Hunter, Lisa Hayes, Miriya Sterling along with Rem. Janice Em later managed to interface with the Awareness and reprogram the planetary defensive system to ignore the Sentinels weapon fire which devastated the Invid occupation forces along with their Inorganics. During the battle for Haydon IV, Sarna was killed and Prince-Administrator Vowad in a rage turned against the Invid with this manifestation taking the form of Zor who destroyed the Invid carrier thus forcing the invaders off the planet.
- The planet features in The End of the Circle novel by Jack McKinney where it was revealed to hold the Haydon race in stasis until after the Invid departed Earth and fell under the control of the Awareness who took command of the Haydonites. Haydon IV was revealed to capable of producing sphere ships by mining worlds and was capable of a Space Fold.