Zs'Skayr (pronounced Zuh Scare), also known as Ghostfreak, was the Ectonurite High Ecto-Lord of Anur Phaetos and Anur Transyl in the Anur System. He was originally stuck in the form of Ghostfreak, as a separate personality that would influence Ghostfreak's actions. Over time, he managed to gain enough control over the form that he could escape from the Omnitrix, becoming one of Ben Tennyson's most dangerous enemies.

In the Original Series, Zs'Skayr had a ghost-like body. It was gray-purple and had black lines running across his chest. His head resembled a grey-brown skull turned upside-down, which had uneven teeth, black lips, and one purple eye. He had long black nails, and there were some tears in his skin, revealing black and white striped tentacles underneath. He could also become smoke-like by deforming his bodily shape into wisps of grey, somewhat transparent flames.

Just after escaping the Omnitrix, Zs'Skayr looked exactly like 10-year-old Ghostfreak. This included the original Omnitrix symbol peeking out of his skin on his lower left chest too, which was not present on his true form.

In Alien Force, Zs'Skayr's body was purple/blue and he had whitish-grey nails. His spine was sticking out of his back, his tail was fully exposed with black and white stripes and he had spikes on his elbows with whiter, less sharp rows of teeth.

In Omniverse, Zs'Skayr had turned his head right-side up. He had two eyes, one on his head and one on his chest, and his skin was now modified to look like the hood and cloak of a stereotypical Grim Reaper, complete with a scythe. The spinous processes on his back were larger and more curved, the skin on his arms were hanged down, much like sleeves, and his teeth looked more like human incisors than fangs.