Indeed. Forrest Gump met JFK. We know JFK existed, so Gump must have existed. And if we object that he was merely fictional, then clearly JFK was fictional too.
At the age of five, Skagra decided emphatically that God did not exist. This revelation tends to make most people in the universe who have it react in one of two ways - with relief or with despair. Only Skagra responded to it by thinking, 'Wait a second. That means there's a situation vacant.'