This sound comes from Terraria, the sandbox action-adventure game released by Re-Logic in 2011. Players widely recognize it as the boss spawn warning, especially in clips referencing the Eye of Cthulhu and other nighttime encounters. The cue spread through gameplay videos, challenge runs, and short-form memes because it communicates immediate danger in just a few seconds. It is still used by creators because even outside Terraria, the sound quickly tells viewers that something threatening, difficult, or wildly unexpected is about to happen.