Alessi

Alessi is a minor antagonist featured in Part III: Stardust Crusaders.

Appearance/Personality
Alessi's most telltale characteristic is his bizarre hairstyle, which resembles a dust mop with decorative beads tied to it in intervals. He also carries an oversized hatchet with him that is engraved with the word 'Ax'.

Alessi is a sadistic, yet cowardly man who will only fight those who are weaker than him, as he feels good when beating them up and because Alessi knows he can win. His terrible personality shows how much he likes to torture someone who hurt his pride, his intention to kill is so great that it can be felt even at a distance. He was showed a strange logic, as Alessi claimed that he himself was weird, but also said that "people who always say they are weird aren't actually weird...So I'm not weird". His stand Sethan represents Tornados and Storms.

Stardust Crusaders
Alessi is hired by Dio Brando to kill Jotaro Kujo and his friends. Alessi first appears bullying kids until he finds Polnareff alone. Sethan extends from Alessi like a shadow, and proves to be a formidable nuisance to Jean Pierre Polnareff, easily allowing Alessi to turn him into a child and hunt him. Alessi also turns a woman who became Polnareff's friend into a fetus, giving Polnareff little time to defeat Alessi before her death. As Polnareff doesn't remember Jotaro he has a hard time fighting alone, but Alessi also turns Jotaro into a child. Even without a stand the de-aged Jotaro, who had a violent personality even as a kid, makes an unguarded Alessi victim to several punches to the face, knocking him out cold. Alessi, upon waking up, finds his stand power was deactivated, with adult Jotaro and Polnareff standing triumphantly before him. He is then subjected to a combined barrage from Silver Chariot and Star Platinum and "punched into oblivion", not being capable of fighting anymore.

JoJo's Bizzare Adventure: Heritage for the Future
Alessi is characterized as a comic-relief character (such as Dan from the Street Fighter) with his ridiculous animations and over the top attacks, but is in fact a powerful character. His active stand possesses incredible range, and can be extended even further by holding the Summon button down while calling it out. It's weakness however: Alessi will not be able to attack aerially with it active since Sethan is a shadow, and cannot leave the ground.

Alessi's Tandem ability allows him to move and attack a very rapid pace for a short period of time at the cost of an energy meter, and even chain it with another of his Super Abilities, Ushi-Ushi-Ushi, which makes Sethan rise from the ground and cause area of effect damage to the opponent. After any of his supers successfully connecting, (excluding Tendum without chaining it to a de-aging attack) his opponent will be shortly turned into a child (or something much more hilarious, such as Rubber Soul being morphed into a portly woman) and rendered defenseless against the onslaught of Alessi's 'Ax'. All of this makes Alessi a potentially deadly opponent in the right hands, and nothing to shrug off. Also he can shoot the opponent up to six or seven times with a gun he pulls out. His normal punch/kick attacks are weak but with Sethan he gets a boost of not having weak attacks.

Notably, not everybody who is hit becomes younger, however. Some people turn into other characters in the story, such as Mariah who turns to the old woman in Egypt that Joseph encounters, or Chaka and Khan, who respectfully turn to the kid and the cow that Anubis possesses before going into the river. Joseph needs to be hit twice for the stand to have any effect, as he turns back to his younger self from Part II: Battle Tendency, and when hit again, turns into an even younger child holding a Superman comic. Alessi can use his stand even after being de-aged by another Alessi, implying he either was born or developed his stand ability at a young age.

Trivia

 * Alessi is the second character to break the fourth wall (the first one being ZZ). Alessi scolds Polnareff for kicking his feces at him, telling him how he would never do that if he was the main character. He's also one of the few characters to do the "rerorero" sound (along with Noriaki Kakyoin, Rubber Soul, and Joushuu Higashikata).