Eye of Cthulhu is a huge eyeball with 2,800 / 3,640 / 4,641 health. It has a 33.33*1/3 (33.33%) chance of spawning at the beginning of each night once a player in the world has 200 max health or more and over 10 defense, and there are 3 or more NPCs living in houses. It will continue to do so until defeated for the first time. It can also be summoned by using a Suspicious Looking Eye at night. If not defeated by the player by the end of the night, it will travel upwards and despawn. This is generally the first boss a player must face. It travels through blocks, and spawns Servants of Cthulhu.