The Black Mass is, in fact, the main antagonist of the Samurai Jack series: it is a living, non-sapient mass made of evil that was the original form of the shape-shifting wizard Aku, who became ruler of the world and Samurai Jack's nemesis. No mortal weapon can harm the Black Mass, as it's power extends far beyond the mortal realm.


The Black Mass appeared in "Episode XXXVII: The Birth of Evil, Part 1" when it started to consume the universe. Before it could succeed in consuming the universe, three deities - Odin, Ra, and Vishnu - arrived to exterminate this great evil. After a fierce battle, the three Gods finally defeated the Black Mass. Unfortunately, the Black Mass was not completely destroyed: a fragment of it drifted away from the battle unobserved and crashed into the Earth approximately 65 million years before the rise of Aku. The subsequent impact is believed to have triggered the K-T extinction period, more commonly known as the event which wiped out the dinosaurs.

As life on Earth began to evolve anew, many people and animals were destroyed by the Mass as it continually expanded, consuming all in it's path. When the Black Mass approached Imperial Japan, Samurai Jack's father, who was the Emperor, attempted to destroy the Black Mass with a poisoned arrow, which only resulted in the Black Mass becoming sapient and aware. The fragment of the Black Mass transformed into a large demon before taking on the name Aku, which means "Evil" in Japanese. He then went on to raze the Emperor's palace and surrounding village. The Emperor was tortured by Aku until the three Gods noticed Aku. They freed the Emperor and made him an enchanted sword, which the Emperor used to banish Aku back into the earth. As a precaution against Aku's possible return, the Emperor trained his son to wield the enchanted sword with unmatched skill, and passed it to him. Aku would rose again later, and during his battle with the Emperor's son, he tore open a portal through time and flung the young prince - and the enchanted sword - into the far future. During that time, Aku eventually conquered the Earth and established an empire of tyranny that lasted thousands of years.

Eventually, in the series finale CI, Samurai Jack was able to travel back to the past to the moment right after Aku had sent him into the future (thanks to the help from Ashi, who was able to inherit Aku's powers as she is one of his daughters). With that in mind, Samurai Jack manages to kill Aku with his sword, destroying what's left of the Black Mass and freeing the universe from its tyrannical control for good. However, this came at a sad price as Ashi starts to fade from existence since she was created from the Black Mass, much to Jack's distraught.


           Samurai Jack Villains

Aku/Black Mass
Demongo | Scaramouche the Merciless | Jack-Aku | Mad Jack | Minions of Set | The Gentleman | X-49 | Beetle Drones | DJ Stylbator | Imakandi | Ultra-Robots | Pig Sheriff | Cult of Aku (High Priestess & Daughters of Aku)

Guardian | Boris | Demonic Spirit | Orc Army | Lava Monster | Huntor | Chritchellites | Cronus | Gordo the Gruesome | Josephine | Lazarus-92 | Aqualizer | Omen | Dominator