God (Tripping the Rift)

In God is our Pilot, Chode and Gus travel back to the beginning of time. Their ship accidentally collides with God and kills Him. But when they return to their own time, they discover that they've actually made things BETTER. Without God, there's no concept of good and evil, and everyone is basically decent towards each other; there's no crime or war or sexual repression. Everything is going pretty well...until Chode and Gus let the cat out of the bag and introduce the concept of sin to the universe, sending it into chaos. They travel back in time to set things right and get killed themselves, and God walks away laughing at their deaths and in the episode titled Santa Clownza he unleash a plague of locusts on a planet because they refused to worship him.