Gregory is very respectful of his master and always speaks highly of him, but he will talk trash to anyone he does not believe is better than him. King Kai called for him after Goku managed to catch Bubbles: the new goal was to hit Gregory with a heavy hammer. Much later Gregory is killed when Semi-Perfect Cell blows up on King Kai's Planet. Although Gregory did not appear in the manga by Akira Toriyama, he was one of the many filler characters designed in the Goku Densetsu by Toriyama and his staff. From Dragon Ball Wiki, a Wikia wiki.