The Order of the Guardians is made up of human fighters, all of which were taught in the arts of ninjutsu. They wear dark blue or black clothing (in modern times, supplemented by a trench coat) and recognizable by the medallion with an image of Utroms that they wear around their necks. As weapons they prefer to use special high-tech katana, which can be charged with an unknown energy to increase their cutting power.
The Guardians are aware of the true identity of their masters, the Utroms, but they serve voluntarily. Promising talents are often recruited from outside the ranks of the Guardians after they've earned the trust of the Utroms.
Hundreds of years ago, a starship carrying Utroms, a sophisticated alien race, crash-landed in medieval Japan. The ship was in fact transporting a prisoner, the psychopathic Utrom Ch'rell, who had escaped and sabotaged the ship. Without a way to repair the ship, the Utroms were forced to mingle in disguise among the people. But having succeeded in stealing an exoskeleton constructed for this purpose, Ch'rell established himself as a human, took the name of "The Shredder" and built a ninja clan to create an army of followers. In order to protect themselves and other innocent people against the encroachments of the Foot, the Utroms in turn founded the Guardians after they had won the trust of some humans. Two Guardians whose career would unleash a whole range of far-reaching events were Hamato Yoshi and Yukio Mashimi, but Yukio eventually betrayed the Utroms to the Shredder. When the Utroms then had to leave Japan, they were followed by the Guardians, who continued to serve their masters in their new hideout, the Techno Cosmic Research Institute, in New York City.
The Guardians finally came into the light as a conflict between the Utrom Shredder and the Turtles begin. Since the Utroms, especially the Council of Three, did not know how they should assess the Turtles, the Guardians were instructed to monitor and, if necessary, to eliminate, if they should join forces with their archenemy. But when the true sentiments of the Turtles came to light, the Guardians were their allies against the Utrom Shredder and also brought Splinter to safety after he was seriously injured in the battle against the Shredder.
A Guardian Ninja action figure was released in 2004.