Jonathan Graves (played by Peter Liapis) is the main protagonist in the movie Ghoulies. Twenty-five years ago, as a baby, Jonathan was about to be sacrificed by his evil father Malcolm, until his mother saved him. Jonathan was saved by Wolfgang, who raised him. Years passed, and Jonathan inherited his late father's house. Later, Jonathan discovered his father's past and was slowly influenced. Jonathan gave up everything, even college, as he continued his study in the dark arts. First, he conjured the ghoulies, then Grizel and Greedigut, who reluctantly told him that in order to gain knowledge and power, he had to perform a ritual with his friends, including Rebecca, who couldn't escape. It turned out that the ritual was to resurrect Malcolm. While his friends were killed off by Malcolm, the elves and the ghoulies, Jonathan chose to bring them back with his father's robe. There he met Malcolm, who was wearing it. Jonathan tried to fight him, but it was no use. When Malcolm was about to kill him, Wolfgang intervenes. As the two magic-users fought each other to the death, the house was collapsing. Jonathan gathered his resurrected friends and they got into their cars and fled for their lives.
He returned in Ghoulies 4 only this time as a retired occultist turned police officer/detective. His latest assignment finds him battling his former girlfriend Alexandra (Stacie Randall), who has escaped an asylum and tries to summon forth the demonic forces Graves trifled with in the first film. He now has to deal with the new pair of ghoulies.