Eclipse was one of the three guardians of Eon, designed as a set of safe-guards to ensure that he didn't go out of control. In such an event, he was designed to take Eon's programming into his own systems and contain it. However, in a fateful incident at Eon's initial full activation, Eclipse took Eon's power source by mistake. Without the safe-guards against this power, Eclipse eventually went insane. Driven by the desire to rid himself of Eon's power but with no way to do so, he sought to revive the Eternal Endgame by using the Guardians' power to create a class of Navis known as "Generationals" as his personal soldiers.
Under the effects of Eon's power, Eclipse is a determined and frightfully powerful Navi. He can freely manipulate space and time to obliterate anything that stands in his way.
Eclipse, along with his fellow guardian Triad, was lost in the final battle against Eon. The two of them sacrificed themselves in order to fix the damage that their charge had caused.