Zero's Geass augments his physical strength by exaggerating the magnitude of macroscopic forces. When active, a Geass signal appears in Zero's right eye.
Zero's Geass Canceler manifests in his left eye and unlike other powers of Geass is represented by an inverted blue version of the bird-like Geass sigil. As Zero's left eye was shown to be a cybernetic replacement, it is assumed that this is also a cybernetic eye, raising the question of whether or not Britannia's Geass Directorate had managed to reverse-engineer Geass, or had simply been developing countermeasures. This ability appears to cancel out all other Geass effects within a given range, hence the name "Geass Canceler". It will automatically reverse any Geass used on Zero.