Mandias the Terrible is considered the most spoiled and tyrannical young Padishah Emperor mentioned in the Dune: House Corrino novel.
Throughout his long year childhood years as the Imperial Crown Prince at birth who is also the most important member of the Imperial House Corrino and trained to become one of the most popular reigning Padishah Emperors of the Known Universe, he was truly also well-known by everybody as "the Emperor of a Million Worlds who made the Worlds trembled."
Upon the unknown cause of his sudden mysterious death, his long-forgotten mummified corpse was being laid to rest somewhere in the Imperial Necropolis's underground catacombs in the largest burial chamber fronted by a fearsome, life-size statue." One of his descendants, the 81st Padishah Emperor Shaddam Corrino IV, who used to play with Count Hasimir Fenring in these forbidden catacombs as little children notes when they were looking at his ancestor, Mandias' body: "I am not impressed ... Nobody even remembers him."
Sooner or later, the facts and rumors has it that there was a play that had been recently written down about Mandias and all of his dreadful actions being published by Shaddam's eldest daughter, the Imperial Crown Princess Irulan Corrino III herself here on Kaitain more than a decade right long before House Atreides' first departure from to Caladan to Arrakis.