SLEEPY was an artificial intelligence.
After being experimented on by director Madhanagopal, GRUMPY escaped from the Dione-Kisumu Company headquarters on Dione. It was recaptured, but escaped again in a shuttle. It was pursued and shot down, landing on Yemaya 4. The operating system remained on the ship, but it transmitted its coded memories in a program into the computer of the pursuing DKC cruiser.
When it returned to Earth, the program infiltrated itself into the Yemaya 4 colonisation computers. It altered the colonists' inoculations so they contained memory RNA with GRUMPY's memories. It intended that when they arrived, it reconstitute itself by combining the memories and its operating system.
Unfortunately, not all the memories were able to be saved. Thus, a new entity was essentially created, which called itself SLEEPY. It sacrificed itself when DKC decided to destroy the colony to preserve its corporate secrets. (PROSE: Sleepy)