"Tachyon" (タキオン Takion) is an archetype focusing on "Number 107: Galaxy-Eyes Tachyon Dragon" and its "Number C" version, "Number C107: Neo Galaxy-Eyes Tachyon Dragon" which are used by Mizar in Yu-Gi-Oh! ZEXAL.
A tachyon or tachyonic particle is a hypothetical particle that always moves faster than light, and most physicists believe they cannot exist because they are not consistent with the natural laws of physics. The word comes from the Greek word tachys, meaning "swift, quick, fast, rapid". This is a reference to the rivalry between Mizar's "Galaxy-Eyes Tachyon Dragon" and Kite Tenjo's "Galaxy-Eyes Photon Dragon".