According to the uploader's note, this roar comes from 'ep. 2 death rises,' a fan-made Godzilla episode in which the villain Dark Ghidorah unleashes its cry toward Grand Island. Fan-created kaiju projects like this one borrow Godzilla's mythology to stage original monster battles, and standout sounds — especially villain roars — travel quickly through edit culture. Clips of this roar get lifted into tribute videos, versus battles and meme edits because a monster's entrance lives or dies on its sound. It endures online as a shorthand for overwhelming, otherworldly menace.