Mold returns in the form of a Spectre as an antagonist in Ultraman X.
Mold and his siblings created the Guar Army for the purpose of conquering the universe. After their plans were foiled several times by the Andros Warriors, Mold fused with hsi siblings to create Guar.
Mold and Gina were both revived as Spectres by Yapool during the events of Ultra Fight Victory but were unable to prevent their younger brother from being killed by Ultraman Victory. Thus, upon arriving on Earth, the two siblings decided to avenge their younger brother and rebuild the Guar Army.
Mold attempted to gather the Guar Army so he could strengthen them with Dark Thunder Energy, but they were destroyed by Ultraman Ginga before they could arrive. Mold later absorbed the souls of his siblings to form Guar Spectre.