Aku was the main antagonist of the Samurai Jack story and a demon who had been spawned from the depths of space. In addition to his classic shapeshifting powers, he also commanded hordes of minions and could even shoot lasers from his eyes.
Throughout the series, Aku has had many stunning victories and crushing defeats. But was he a worthy opponent for Jack and a realistically world-conquering threat? His greatest victories shed light on the havoc he has wreaked across the cosmos.
10 Victory: Aku Successfully Sent Jack To The Future
During the first battle between Jack and Aku, it seemed as if the villain was doomed. Regardless of what shapeshifting forms he took, the Samurai managed to strike him down and reduce his body to charred ash through the blessing of his sword.
At the last second, Aku sent him to the future through the usage of a time portal. Consequently, Jack was forced to fight for his life for over half a century before finally returning to his home and vanquishing the demon once and for all.
9 Defeat: Aku Was Humiliated By Jack In Human Form
Realizing that their battles were in an endless cycle, Aku challenged Jack to a fight without his sword. After some consideration, the Samurai agreed under the condition that Aku must remain in human form.
Their showdown occurred in the ruins of a desert. Jack immediately got the upper hand once the duel began, compelling the demon to cheat however necessary in order to turn the tide. It wasn't long before Jack caught on, retrieved his weapon, and forced Aku to flee into the horizon.
8 Victory: Aku Killed The Guardian Off-Screen
The Guardian was a large blue alien responsible for protecting a time portal. He managed to defeat Jack with a combination of brawn and skill during their first battle.
When the hero neared his location a second time five decades later, he found the man's ruined glasses littered on the floor. Considering it was previously mentioned that Aku destroyed all remaining time portals in existence, it follows that at some point in the fifty-year time skip, he fought with and murdered the Guardian. Consequently, Jack was denied a rematch and a means of returning to his childhood home.
7 Defeat: Aku Lost Against Jack At The Graveyard After Wasting His Chance
After exhausting Jack with undead hordes, Aku managed to steal his sword and pin the hero to the ground. With a cruel smirk, he relished the opportunity to kill his opponent with his own weapon.
To the combatants' mutual surprise, the sword would not pierce Jack's chest since it didn't cut pure souls. As a result, the Samurai was able to wrangle it from the demon's grip, turn the fight back in his favor, and force the villain to retreat. Aku's defeat was especially humiliating since he wasted one of the few chances he had to kill Jack.
6 Victory: Aku Killed The Scotsman Instantly
The Scotsman was one of Jack's longest allies and Aku's most troublesome enemies. Based on what he told the Samurai, he was just as wanted for disrupting the current regime as his friend was. Moreover, he raised an entire army of children into fine warriors to wage his campaigns.
When Aku finally found him, the Scotsman hurled a plethora of scathing and demoralizing insults. Unfortunately, words would not stop the villain from reducing him to ash with laser beam eyes.
5 Defeat: Aku Was Betrayed By The Imakandi
The Imakandi were a race of tribal warriors who were recruited by Aku to hunt and capture Jack. After a great deal of struggle, they managed to corner the hero and infect him with pacifying venom.
However, the Samurai had put up such a fantastic challenge that they sought to honor their bond as predator and prey. When Aku came to collect his prize, they refused to hand Jack over and instead teleported him to their home planet. Aku was particularly infuriated because one of his best opportunities to kill his nemesis had been squandered.
4 Victory: Aku Deceived Jack Into Helping Him Destroy A Time Portal
In order to approach Jack safely, Aku took the disguise of a beautiful woman and helped the Samurai against his own minions. This won his trust and compelled him to invite "her" along for his latest lead on a nearby time portal.
When the two finally arrived, Aku promptly killed the portal guardian and destroyed the gateway. He gloated of his deceit before a horrified Jack and mocked him for his foolishness. Given how similar the feminized Aku looked to his real counterpart, he had a point about making fun of Jack's intelligence.
3 Defeat: Aku Was Nearly Killed When Overestimating Jack's Jumping Skills
Initially, Aku used his height to mock Jack by dangling a time portal just over his head. He understood that despite his rival's speed, he wasn't able to leap far from the ground.
After training in the jungle, Jack managed to perfect his jumping skills. During his next confrontation with Aku, he leaped into the air and nearly took off the demon's head. It was an excellent demonstration of how Aku's arrogance serves as his biggest detriment and nearly bought Jack a premature return to the past.
2 Victory: Aku Captured Jack & Humiliated Him In Front Of The Entire World
When Aku uncovered that Jack had been traveling with Ashi, he realized a rare opportunity to defeat him. By invoking Ashi's demonic nature, he was able to bend her to his will and force her to fight her beloved.
Jack knew that if he fought back, he would be forced to kill Ashi. Therefore, he surrendered himself, allowing Aku to finally take him prisoner and announce his execution before an entire planet of horrified onlookers.
1 Victory: Jack Was Successful In Killing Aku & Returning To The Past
After Jack's allies came to save him, he managed to release Ashi from her corruption and have her summon a time portal. They escaped through the gateway together, returning to the past moments after Aku had initially banished him.
Aware of his treachery and livid over his atrocities, Jack ruthlessly attacked Aku, ripping apart his demonic body until nothing was left. While he managed to destroy the demon, the end of his existence meant that Ashi was erased as well. It ended the series on a poignant albeit fulfilling note.