| Encyclopedia Galactica
THE MULE -- Less is known of The Mule than any character of comparable significance to Galactic history. Even the period of his greatest renown is known to us chiefly through the eyes of his antagonists and, principally, through those of a young bride. It was after the fall of the First Foundation that the constructive aspects of the Mule's regime took shape. After the definitive break-up of the first Galactic Empire, it was he who first presented history with a unified volume of space truly imperial in scope. The earlier commercial empire of the fallen Foundation had been diverse and loosely knit, despite the impalpable backing of the predictions of Psychohistory. It was not to be compared with the tightly controlled Union of Worlds under the Mule, particularly during the era of the so-called Search.
The Mule is an antagonist that shows up particularly in Foundation and Empire and Second Foundation. He is described as having an abberrant genetic mutation, which allows him to control other people's emotions and moods. He comes to prominence about 150 years after the establishment of the Seldon Plan, and his actions threaten the whole plan, since Hari Seldon could not have predicted him due to his being a genetic mutant. He calls himself the Mule because just like mules, his genetic mutations has left him sterile.
The Mule was born on the mentalic planet Gaia within Sayshell sector, where he was regarded as a criminal. By some means he managed to escape the planet at a young age and use the innate powers of its inhabitants against the Galaxy.
Motivated by awareness of his abnormal appearance and hatred against the galaxy, the Mule used his extensive powers to rise to power and conquer even the First Foundation. The Mule uses his telepathic ability to carve his own empire out of nearby territory, sweeping aside the remnants of the Galactic Empire centered around Neotrantor. The Mule based his rule on the planet Kalgan, which he obtained by mentally converting the warlord of Kalgan. After conquering the First Foundation, he made Kalgan the capital of his Union of Worlds and styled himself First Citizen of the Union. Leading up to, during, and for a good time after the Mule's conquest of the Foundation and its trade confederacy, no one ever actually saw the Mule or knew what he looked like.
Following his conquest of the Foundation, the Mule attempted to locate and destroy the Second Foundation. In the end the First Speaker of the Second Foundation mentally altered him, whereupon he ended his quest and governed as a benevolent dictator until he died a premature death resulting from his mutation.