When you see them from a distance, moon lord and cthulhu are big baddies with evil plans for the world. But are they really one and the same? I say yes. Moon Lord summons true eyes of Cthulhu when you kill its eyes, and the bosses are brain of cthulhu and eye of cthulhu. Also, in the game lore, it says that the dryads teamed up against cthulhu and weakened him. They sent him to the dark side of the moon where he regained his powers, and so, it makes sense that Moon Lord is Cthulhu.