Trilobite Magia are combatmen-type Magia and antagonists in Kamen Rider Zero-One. They are created when a Magia overrides other HumaGears by hacking them with its tendrils.
When the Berotha Magia first emerged, it hacked the surrounding HumaGears and turned them into Trilobite Magia to cause havoc. The Trilobite Magia were defeated by Kamen Rider Zero-One, but one survived and attempted to attack Jin, who finished it off by shooting it through the head. The rest of the Trilobite Magia were destroyed by A.I.M.S. forces led by Isamu Fuwa and Yua Yaiba.
Several more Trilobite Magia were created by the Neohi Magia after it shot off its tendrils from a rooftop and transformed the surrounding HumaGears into Trilobite Magia. However, the Trilobite Magia were soon destroyed by Kamen Rider Valkyrie.
A group of Trilobite Magia appeared to attack Aruto Hiden, Isamu Fuwa, Go Sakurai, and HumaGear Anna as they entered the sealed off Daybreak Town. However, Aruto transformed into Zero-One and stayed behind to fight them off while the others went to investigate the true cause of the Daybreak incident. Anna was later transformed into a Trilobite Magia by the Onycho Magia, but managed to resist the malicious programming long enough to play the recording of a data chip they had uncovered. She was then finished off by Kamen Rider Horobi to prevent her from exposing any more secrets.
- The Trilobite Magia is the first Trilobite-themed monster since the Trilobite Undead from Kamen Rider Blade.
- The Trilobite Magia does bear some resemblance with a rogue NS-5 from I, Robot.