Exclusive to the Lost Galaxy/Lightspeed Rescue teamup episode Trakeena's Revenge, Triskull is a Demon warrior who swears allegiance to Trakeena. He is the leader of the ghouls, foot soldiers Trakeena uses with the destruction of her Sting Wingers. Triskull and the Ghouls were freed from the Shadow World, presumably by Trakeena, only to appear in our dimension on Mirinoi. He pretends to aid Olympius in collecting energy for Queen Bansheera, but is actually collecting it so Trakeena can return to her insectoid form. He attempts to stop the Rangers from entering the building, where the energy is kept, and is destroyed by the Red Galaxy and Lightspeed Rangers.
Unlike most villains and monsters, Triskull did not explode after being killed by the Rangers. This was because his Sentai counterpart survived the attack, but died by commiting suicide in order to complete the ritual.
It should also been noted that Triskull was the one who shrunk the people and his death should should have also freed them once Carter and Leo defeated him.