The world of Samurai Jack is a visually striking, genre-bending dystopia ruled by the shapeshifting demon Aku. It blends highly advanced, neon-lit sci-fi with ancient mythology. Humanity lives under brutal oppression, where technological marvels are paired with severe scarcity—to the point that the mafia even profits from controlling drinking water.

Samurai Jack: A feudal Japanese prince and master warrior flung into a dystopian future by Aku. He wields a mystical katana forged by the gods. He's a fairly tall and lean man with a fit build and has long jet black hair that he keeps tied in a Japanese chonmage. Jack's clothing consists of a simple white and gray gi in the style of a kimono, a white obi around his waist, and a pair of wooden geta.

Aku: The shape-shifting "Master of Darkness" and main antagonist who rules the distant future with an iron fist. Aku's 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.

Ashi: One of the Daughters of Aku who breaks free from her mother's cult, allies with Jack, and becomes his love interest. Ashi shares her appearance with the Daughters of Aku. She has a slim, petite build, and large, narrow eyes, red lips, and are 'wearing' some sort of black bodysuit. Ashi's hair is combed up to a single point initially.

The Scotsman: A boisterous, foul-mouthed warrior who becomes Jack's closest friend and ally in the future. The Scotsman appears, for all intents and purposes, to be a man from Scotland. He is a large man with receding red-orange hair tied back in a ponytail, a matching short beard with the chin shaved, a barrel chest, and disproportionately small legs, the left of which was replaced with a submachine gun presumably after losing it in a battle. He wears a white shirt with torn sleeves, a traditional Scottish kilt with a sporran (frontal pouch) in the shape of a grinning cat's head, and a single boot with a buckle over his human right leg. He also has body hair on his chest and arms that are reddish-orange.

He is a robotic, flute-playing assassin sent by Aku to destroy Jack. Scaramouche is a very tall, robotic warrior, standing over a head taller than Jack, who himself is above average in height. His appearance is similar to X-49, but with teal (Or white depending on whether or not he has a body) eyes instead of red, a longer neck and a larger functional mouth with teeth and a blue-green (Later red) tongue. He wears a black conical hat, orange scarf, red high-heel boots, a long purple overcoat coat with red interior and a large black belt. Inside his belt holsters his tuning sword, while his larger sword is stationed on his back.

The High Priestess: The leader of the cult who worshipped Aku and birthed the Daughters of Aku. She wears a black robe, white mask and a head covering with horns resembling Aku's, except her head covering had six horns instead of four like the other members (possibly signifying her role as the leader of the cult).

Demongo: A soul-stealing minion of Aku who commands an army of spectral warriors. His head is detached from the rest of his body, which is largely concealed by a cloak. Demongo's eyes and mouth are blue, as is the flame on top of his head.

The Daughters of Aku are seven deadly human-demon hybrid assassins born to the High Priestess of Aku in season 5 of Samurai Jack. Birthed after their mother drank Aku's essence, their names are Ashi, Ami, Ani, Aki, Avi, Ali, and Ari. They were raised to kill Jack, but Ashi eventually joined him.