Aku is the main antagonist of the series Samurai Jack. Born from The Black Mass of Darkness, Aku was an evil, shape-shifting demon who took over the world and ruled it for countless eons, the arch-nemesis of Samurai Jack and the biological father of Ashi and her septuplet sisters. Aku constantly antagonized Samurai Jack: he often attacked him when he was weak, and other times defended himself from Jack's own gambits. Prior to Ashi sending Jack back in time to vanquish Aku's past self, the two seem doomed never to defeat each other, and while Jack had beaten Aku on numerous occasions, Aku merely transformed into a creature, retreated, and usually called out a taunt over his shoulder. Aku was entirely aware of his inability to defeat Jack and even lamp-shaded that in "Episode XLVIII: Jack versus Aku", which eventually discouraged him from fighting Jack further. Aku could have been considered the Deuteragonist of the series as a whole (albeit a rare, villainous one), as while Ashi became that in Season 5. Aku had the most focus in the narrative besides Jack. While he's usually presented as a serious and threatening foe, Aku was also a source of comedy in the show, due to his outrageous design and sometimes wise-guy behavior, that was supported by Mako's over the top voice-acting. Aku means "Evil" in Japanese. It is written as "悪" in Kanji. The kanji can also be pronounced as "Waru". In Samurai Jack: Battle Through Time, Aku made a last ditch attempt effort to save his existence and secure his rule in the future. Aku was Evil Incarnate; he embodied the very essence of an evil overlord. Cruel and domineering to all that he met, it was obey or be obliterated with Aku. Arrogant, temperamental, callous, and sadistic by default, Aku ruled the Earth for thousands of years and did not take kindly to disobedience. Aku was responsible for countless genocides, with cities, towns, villages, and small settlements being completely destroyed, alongside all their inhabitants, while nature itself was left to rot or was decimated in order to make room for Aku's strongholds. It was likely that religions were also affected, given Aku's loathing toward all that was good and sacred. Furthermore, lack of any divine intervention from the Gods allowed Aku to conquer Earth and rule its inhabitants with an iron fist. While Aku had recreated numerous lands into his own image, he was often just as satisfied with leaving entire areas barren wastelands and saw the carnage as reminders of his power to the general populace. Atrocities were a daily occurrence since Aku's rule, as he welcomed wanted criminals from across the galaxy, provided them with areas that were still fully occupied, and entrusted the new arrivals to wipe the inhabitants from the Earth. When he was faced with opposition, Aku found enjoyment in slaughtering thousands of rebel armies with ease, and often made one's circumstances even worse than death if they still longed to fight him. Such was the case of the Lava Monster who fought against Aku, even as Aku decimated all of his warriors. As punishment, Aku encased the man in a crystal and forced him to watch as he slaughtered everyone that he loved, destroyed his kingdom, placed him within the depths of a mountain, and refused to grant him a warrior's death. A similar action was performed shortly after Aku's true birth: he forced Jack's father, the Emperor, to watch him begin his reign of terror on his homeland. To increase his already formidable power, Aku also plundered the world, and countless other planets, of its resources and enslaved surrounding species to do the heavy lifting. Those that refused were often tortured and executed, as with the case of Jack's people and canine archaeologists. Numerous scientists were recruited, so that Aku may leverage their intelligence in order to create an unstoppable army of robots to take over various lands considerably quicker and eliminate more carefully hidden pockets of resistance. Aku's powers were even able to conjure up demons or monstrosities, who were then unleashed upon the land in order to create further sorrow and misery. Aku was outright unhinged, merciless and inhumane, to say the least, but had enough of an understanding of humanity in order to manipulate the feelings of others: Aku often blackmailed others in performing his will and then betrayed his promises to them once they fulfilled their services. Aku was as intelligent as he was powerful, and his cunning knew little end, from taking the form of a woman in order to trick Jack or manipulated various races into serving him. Aku was also dishonest and had no shame or remorse, and routinely went back on his word either to serve himself or simply for amusement. Aku took excessive pleasure in slave labor and enslaved countless races across the universe. Those slaves were often forced to build monuments in Aku's likeness and mined precious resources. When they failed to do so, the slaves were punished terribly and were sometimes executed, such in the case of the talking canines. The slaves of Aku's empire often died due to exhaustion or lack of food and were replaced with more slaves. Aku particularly enjoyed doing this to great or powerful people such as the Emperor and saw it as the ultimate insult by allowing royalty to spend the rest of their lives as helpless slaves. Despite that, Aku possessed a dry sense of humor and often joked when he was in a good mood and mocked Jack whenever or however he could. For instance, in Episode XIV: Jack Learns to Jump Good, Aku held a time portal just out of Jack's reach just as Jack jumped for it. Aku was also rather "genre savvy", and occasionally leaned on the Fourth Wall or lamp-shaded either his own villainous tendencies or various cliche situations. Aku was also a frequent source of comic relief in the show, due, in prime, to his reactions to the things around him. While Aku seemed to have a soft spot for children at times, that seemed to be most indicative of his views of seeing immense value in not simply eradicating them, but rather to convince them via various means to view him as the "hero" of the planet and not Samurai Jack and make them useful servants in the future in order to shape successive generations. That was seen in Episode XIII: Aku's Fairy Tales, where Aku attempted to make children admire him and told them tales that depicted himself as a hero and Jack as a villain. Unfortunately for Aku, the children weren't impressed hearing his increasingly ludicrous tales, which then caused him to vanish in rage after he roared "the end". In Episode XXVIII: Jack and the Rave, Aku composed an evil techno music that hypnotized children, which, again, showcased his lust to indoctrinate young kids into his evil ways and made them dance for him and commit crimes. In Episode C, Aku seemingly welcomed Ashi as his own flesh and blood, and was even delighted by the fact that he had daughters of sorts. Aku fondly called Ashi "sweetheart" and himself as "daddy", but that choice of words could have been chosen to further upset Ashi and Jack. However, Aku had no qualms about manipulating his newly revealed daughter into fighting Jack while he lamented that his child had fallen for his sworn enemy. Despite that, Aku's many genocides of countless nations included children as well and Aku had previously targeted a younger Samurai Jack shortly after the subjugation of his homeland while knowing the threat that the son of his former nemesis, the Emperor, would pose to him if he was left unchecked. After 50 years of battling Jack, Aku's personality seemed to be largely unchanged and appeared to be more mellow, though he appeared to have sunk into something of a depression due to Jack's agelessness, which caused Aku to stop caring about being the ruler of the world. Aku had a more noticeably annoyed and fed up expression on his face and his attitude reflected that: where once before, he would have killed whoever had displeased him, in that state of annoyance. Aku instead got annoyed that the Mud Aliens had dirtied the floor of his lair and told them that he "just had it vacuumed!" and then angrily told them to leave. That also extended to the robots that were sent to kill Jack, as Aku had stopped caring about the new tech that his scientists had created in order to battle Jack and once told them: "And I care, because?". While he claimed at one point not to care about Jack's fate, Aku was actually deeply disturbed by that discovery, as his long experience with Jack had demonstrated that his foe was unlikely to fall into the hands of any of Aku's Minions, which left the two of them in a potentially eternal stalemate. The idea that he and Jack would have to spend eternity fighting had gotten to Aku so badly that he actually split himself into two and had the other half become his therapist in order to do check ups on his mental health. That depression appeared to have caused a degree of apathy in Aku, or at least unhappy resignation, as Aku apparently knew that the population of Earth was beginning to rebel against his rule, but he was either unable or unwilling to do much about it personally due to having lost track of Jack. Aku's depression also made him avoid contact with others beings from outside his palace in which he made the giant voice recorder in his likeliness that recorded his message that said that he didn't want to meet anyone and asked them to go away. At the same time, Aku also cared less about tributes to him. Despite that, Aku's simply sadistic tendencies appeared to be largely intact, as he appeared to be quite pleased with himself after he incinerated the Scotsman and destroyed most of the army that attacked his fortress. However, even that tendency appeared to have been reduced to a considerable degree, as Aku appeared to be more nonchalant than pleased during his destruction of the rebel army. After he was confronted by the Scotsman, Aku either completely forgot to kill the Scotsman's Daughters, or simply didn't bother out of disinterest. Additionally, Aku was shown at one point becoming upset with a group of mud creatures who, in presenting him with tribute, had dirtied a recently vacuumed floor. But instead of having the creatures killed or imprisoned as he seemed to do to others in the past on a whim, Aku merely shouted at them to leave. After he heard of Jack losing his sword from Scaramouche, Aku nearly reverted to his own self and happy to the point of dancing around with Scaramouche. However, after he discovered that Jack had regained his sword, he then angrily blasted Scaramouche into oblivion. During that time, Aku was shown to be cautious enough not to engage Jack in battle head-on and instead relied on controlling Ashi to deal with Jack in order to toy with him as well as cunningly knowing the fact that Jack would try his best to avoid hurting her. At the same time, Aku also lost interest in fighting Jack since he tried to leave after he saw Jack with his sword again and knew full well the result of the fight. Although he was an absolute ruler of the world, Aku was not above paying bills in order to use services, like when he paid the phone bill that allowed Scaramouche to talk to him or ordered bounty hunters to kill Jack. It was also shown that Aku was courteous enough to hold the phone while he waited for service to respond. Shockingly, in Episode C, Aku was even polite enough to state his absence, not to mention an apology for any inconvenience of not being able to meet Scaramouche in person, though he ended the recording and screamed at the listener to leave. Though Aku was capable of shifting his form into virtually anything that he wished due to his metamorphic body, his standard form after he self-upgraded and adapted to the Earth was roughly a humanoid being with a black body, a green mouth, and a red beard which extended from the bottom of his chin. Aku had six horns, four long and two short, that extended from his head, and his eyebrows were made of red, flickering flame. Aku typically assumes a humanoid form, concealing his entire lower body in a massive, thick robe that sometimes manifested as flames. There is one known instance where Aku removes the robe to reveal his thin legs in "Jack and the Zombies". Aku can stand several stories tall and a deep droning noise was often heard around him when he appeared. Long ago in the vastness of space, a great, formless, mindless entity of evil arose. Before it could do harm to the universe, it was set upon by three deities, each one originating from Norse, Egyptian, and Hindu mythologies: Odin (the father of Thor), Ra (the Sun God), and Rama (the seventh avatar of Vishnu the preserver). The three deities fought a fierce battle against the black mass and burned the entity almost completely out of existence with their divine power. However, during the battle, one small fragment of the entity was incidentally cut from the whole by Odin and was never burned away. Unnoticed by the three deities, that seemingly small fragment floated away from the site of the battle and drifted through space for an untold amount of time, until it eventually, and violently, crashed on Earth during the Cretaceous Period in the Mesozoic Era. It was implied that the fragment of the black mass is the very object that caused the extinction of the dinosaurs, although the crash occurred in prehistoric Japan as opposed to the Yucatán Peninsula by a massive asteroid. Over eons, the fragment evolved into an ever-growing ominous forest of black tree-like spikes, which surrounded a tar-like pit at its center, that devoured any living thing that dared to enter. Eventually, the forest grew so large that The Emperor (Jack's father) decided to kill the evil at its source. After he was armed with a poison elixir that was given to him by a Buddhist Monk, the Emperor, with his cavalry, rode into the forest. As they rode, the forest began to gradually kill off the Emperor's men and left the Emperor himself as the only survivor. Once he arrived at a black lake in the forest's center, the Emperor doused one of his arrows into the elixir that he was given and fired it into the black lake, with him believing that it would destroy the evil forest. Unexpectedly, the poison arrow's magic had the unforeseen effect of galvanizing the evil mass into a humanoid form: it gave it intelligence, sentience, and shape-shifting abilities. This entity proclaimed itself with the name of Aku and thanked the Emperor for inadvertently helping him. The Emperor then attacked Aku, but with nothing more than his mundane and mortal weapons, he couldn't inflict any harm upon Aku. Aku then easily defeated the Emperor and strapped him to the side of a tree so that he could watch as Aku began destroying his kingdom and slaughtering his people. However, the Deities, after they sensed the good in the Emperor, summoned him with the aid of Odin's horse, Sleipnir. After the Deities took the good from inside the Emperor, they then used their powers in creating an Enchanted Sword that was capable of harming Aku. After he was armed with the sword and a magical suit of armor, the Emperor plunged into battle against Aku. In the end, the Emperor was victorious and imprisoned Aku into the devastated wasteland in the form of a jagged black tree. As he was sealed away, Aku vowed that he would one day return. During the battle, The Empress gave birth to a son. After he was determined to learn from the catastrophe, and was aware that Aku would indeed one day return, the Emperor hatched a plan while orchestrating the events that would set Jack on his eventual years of training.