Zs’Skayr is an Ectonurite terrorist who is notoriously one of the most dangerous beings in the Galaxy, rivaled only by Vilgax himself. He attempted to take over his entire Solar System, known as the Anur System, including all of its planets and citizens, with the help of Lord Transyl. After he was overthrown, his body was burned alive and presumed dead, until it was scanned by Myaxx (one of Azmuth’s assistants) to be a DNA sample for the Omnitrix.

Due to his Ectonurite nature, his consciousness resided in the DNA, waiting to be awakened by the user of the watch, that being Ben Tennyson. When he was finally unlocked, he contacted his old crew and forced himself out of the Omnitrix, becoming half dead in the process. He seeks to possess Ben and recombine the rest of his DNA to become whole once again and take over not only his system, but the whole Universe itself.

Zs’Skayr is almost 500 years old.

Zs’Skayr’s reign over the Anur System resulted in many horrors that haunt the system to this day. This includes the destruction of Lobo, resulting in the Loboans relocating to its forest moon, the enslavement and near extinction of the Transylians, and a Corrodium explosion so powerful it destroyed most of Anur Transyl, the largest planet in the system.

Zs’Skayr was in league with Lord Transyl, king of the Vladats, in an effort to share custody over the system. But Zs’Skayr betrayed him, resulting in the inhabitants of the Anur System to overthrow Zs’Skayr and kill Lord Transyl. They also made the Vladat race extinct.

Myaxx chose Zs’Skayr’s corpse to be the Omnitrix DNA sample because Ectonurites are highly reclusive and isolated, so his body was the only thing Myaxx could scan.

When Ben unlocked Ghostfreak, he became addicted to transforming into him. This was due to Zs’Skayr slowly implanting himself in Ben’s mind. Once he escaped the Omnitrix, Ben regained full control and stability with this form.

Ghostfreak was a lot more powerful when Zs’Skayr was bonded to him. When Zs’Skayr escaped, Ghostfreak’s DNA was incomplete, so the Omnitrix artificially filled in the gaps of his DNA to make him usable. The benefit is that Ben has complete control over him, but now Ghostfreak has less abilities and is weaker than before.

Zs’Skayr is a deranged psychopath, anyone whom he considers as worthless is either tormented for his amusement or is manipulated and later destroyed once their usefulness has ended. Zs'Skayr is highly vindictive and vengeful, a side of him which is especially heightened through his vicious and bloodthirsty personality. His obsession with possessing Ben, besides becoming whole through access to the Omnitrix, is rooted in his spite over his original entrapment in the Omnitrix and his desire to make Ben feel the same way.