Optimus Prime is the Autobot leader from Transformers, the franchise that began in 1984 with toys and an animated series built around robots disguised as vehicles. The distinctive transforming sound became one of its most recognised effects, recreated across later cartoons, films and games whenever characters change form. Online, the clip detached from full episodes and became a reusable meme sound for reveals and upgrades. Its lasting appeal comes from instant recognition, even a two second burst tells viewers something ordinary is becoming something far more powerful and heroic.