X/Sonic.exe is the main antagonist of the creepypasta by the same name. He is an entity created from an extraterrestrial cataclysm, a being of pure evil who is obsessed with Sonic and uses his visage to commit horrid acts onto his friends and enemies alike. He basically looks like Sonic, but with darker fur, pitch black eyes with two glowing red dots as irises with very tiny pupils. He produces blood under his eyes, and has yellow teeth (both are side effects from when his body was first made).