The growl comes from The Meta, the silent, heavily armoured antagonist of the long-running Rooster Teeth web series Red vs Blue, and appears in season 10 episode 8. The character rarely speaks, so a sound like this carries much of his threat, and fans lifted the short clip for reuse outside the show. It spread through soundboards and fan edits, where its recognisable, inhuman edge made it useful shorthand for a powerful enemy. It remains popular because it delivers menace in under four seconds without needing any dialogue or context.