Xtra HERO (X・HERO, Ekusutora Hīrō) is a sub-series of the "HERO" archetype that is comprised completely of Link Monsters. It is the first, and currently only, sub-group of the "HERO" archetype that has not been used by any character in any of the anime or manga, and is the first "HERO" theme to be introduced since the Yu-Gi-Oh! GX era (excluding the illegal "E☆HERO" monster and "Contrast HERO").