The Night of the Eyes is a randomly-occuring event that takes place over the course of an entire night. It can only start once the Eye of Cthulhu has been defeated. It is characterised by the presence of Demon Eyes flying in the background, as well as waves of eye-based enemies spawning if the player is on the surface. On top of eyes being spawned in said waves, their spawn rate is also drastically increased. By default, no other surface enemies will spawn during the Night.
Later in the game, Eyes of Cthulhu may spawn as well. In hardmode, Wandering Eyes will spawn, and once the player has defeated them for the first time, the Twins.
