The Evil Entity was an evil Anunnaki that was imprisoned within a crystal sarcophagus, buried beneath Crystal Cove. He is the true main antagonist of Scooby-Doo! Mystery Incorporated!. His plan was to destroy the entire universe and devour many planets. Whenever anything or anyone bonds with him will become consumed by his power and get killed in the process of the possession. In the tv series, he was imprisoned in a crystal sarcophagus by the Anunnaki who were good and pure many decades ago. In order to be free again, he manipulated groups of humans and their mascots into doing his biddings: the Mayan Hunters of Secrets and their jaguar Spot, the Fraternitas Mysterium and their donkey Porto, the Alianza Mysterio and their skunk El Fuchi, the Mystery Gang and their bull Tiny, the Benevolent Lodge of Mystery and their orangutan Mr. Peaches, the Mystery Fellowship and their cat Whiskers, the original Mystery Incorporated and their parrot Professor Pericles and the current Mystery Incorporated and their dog Scooby-Doo. The Hunters of Secrets were the only ones who were the most pure and the first to find out that they were being manipulated by the monsterous demon. Instead of setting it free, they decided to destroy the sarcophagus with the Heart of the Jaguar. However, they were interrupted by the conquistadors who came and found the sarcophagus, and took it, believing it to be a great treasure. They later buried it beneath Crystal Cove where its evil has infected most of the townspeople like a poison. After being set free by Professor Pericles and all of planets in the solar system aligned, he plans on possessing Scooby-Doo, but Pericles volunteered to be the host instead. He then killed and comsumed Professor Pericles' body, mutated him into a monsterous squid-like form, and nearly destroyed the universe by devouring the entire human race. However, Scooby-Doo, with his friendship with Shaggy, Velma, Fred, and Daphne combined, ultimately destroyed the sarcophagus with the Heart of Jaguar spear and sent the Evil Entity into oblivion thus creating a new timeline in the process.
- He is voiced by Clancy Brown.
- The Evil Entity will become Winnie the Pooh's enemy in Pooh's Adventures of Scooby-Doo! Mystery Incorperated!
- The Evil Entity will become Ash Ketchum's enemy in Ash's Adventures of Scooby-Doo! Mystery Incorporated!
- The Evil Entity will become Littlefoot's enemy in Littlefoot's Adventures of Scooby-Doo! Mystery Incorporated!