In a post-nuclear future, human race has made many steps. Normal people have become slaves, while genetically modified giants rule the world. Gunpowder is a distant memory and martial arts is the only weapon a man can count on. Two schools face each other in the battle for dominion: Hokuto and Nanto. Kenshiro is the rightful successor of Hokuto school, while Shin is Nanto's. Shin stole Ken's girlfriend Julia and Ken is looking for her. Kenshiro travels the barren wasterland of post-apocalyptic Earth as seeks to rescue Julia. As the series progresses, we are introduced to the six Grand Masters of the Nanto Seiken school, as well as Kenshiro's three adoptive brothers, also trained in the art of Hokuto Shinken. Eventually, Kenshiro's ultimate rival becomes none other than his eldest brother, Raoh, a would-be conqueror who does not recognize Kenshiro as a worthy succcessor.

[Source: Anime News Network]

Following a cataclysmic nuclear war, the world teeters on the brink of complete destruction. Civilization is polarized into a degenerate society where opposing packs of marauding scavengers prey on helpless, homeless nomads. For those who are lucky enough to survive the constant brutality and danger, it is a bleak existence. Life an death blur into abstractions. The only hope left for mankind is to find a hero worthy of becoming the next "Fist of the North Star" - an enlightened warrior - who is capable of leading those with the will to survive out of this barrenness into a new world. But in this savage no-man's land of shifting loyalties and power-hungry demi-gods, heroes are in short supply.

[Source: AniDB]

In the second series after Raoh has been defeated by Kenshiro a new rival appears. The Gentou Kouken warriors. Falco the successor of the Gentou Kouken takes orders from an evil ruler by the name of Jacko. He claims to be the man chosen by the Tentei and issues orders to his subordinates to capture anyone living in order to build up his Imperial Capital. Kenshiro once again rises out of the shadows and puts an end to his tyrannical ways. Amidst the mayhem Lynn gets captured and gets taken to the land of the Shura where only ruthless fighters exist. Now Kenshiro must pursue the captor and defeat the 3 Rasho of the land in order to escape with his life and with Lynn.

In a post-apocalyptic Earth, the water has become entirely toxic, except for some kept safe in a reservoir. A fortified zone has been created by a man named Sanga, he calls it The Lastland. A group of villagers have discovered safe water, and Sanga wants it. He and his band of killers go to kill everyone and steal it. As they do a mysterious man appears out of nowhere, instantly killing some of Sanga's men. His name is Kenshiro, and he can beat any man with his martial art, Hokuto Shin Ken. Sanga will do anything for the water, and Kenshiro will do anything to try and stop him.

[Source: Anime News Network]

Kenshiro is the heir of the legendary martial arts known as Hokuto Shinken, which can kill a man with a single blow, by striking the pressure points in the enemy's body. Hokuto Shinken can be passed only to one successor at a time. When he was chosen as the successor, he parted ways with his brothers, Toki and Raoh. The former decided to use what he knew of the art to cure people... while the latter has chosen to use his supreme strength to install peace in the world by power.
Kenshiro is accompanied by Lynn and Bart, and the movie's story begins when an overlord starts kidnapping children to use them as slaves for building his own pyramid...

[Source: AniDB]

The second part of the new Hokuto no Ken pentalogy. The story of this OVA centers around Yuria.

[Source: Wikipedia]

The third chapter of the pentalogy (3 Movies + 2 OVAs). A retelling of Kenshiro's final battle with Raoh.

[Source: Wikipedia]

This short 6 minute 3D CGI film of Kenshiro’s final battle with Raoh was created in 2006 and came out on DVD in 2007. This will most probably remain an exclusively Japanese release.

[Source: Hokuto No Gun]

The fourth part of the new Hokuto no Ken pentalogy (3 movies, 2 OVAs).

Last of the Shin Kyuuseishu Densetsu pentalogy. A prequel set between Kenshiro's defeat at the hands of Shin and the beginning of the manga.

[Source: Wikipedia]

Super-deformed version of Hokuto no Ken, Buronson & Hara Tetsuo's post-apocalyptic fighting manga.

Note: The "DD" stands for "Design Deformation," since the characters are only "two-heads-tall."

[Source: AniDB]

It's a special project commemorating the 30th anniversary of Hokuto no Ken.

[Source: MyAnimeList]

A "double title" adapting both "DD Fist of the North Star" and "Fist of the North Star: Strawberry-Flavored".

[Source: Animate.tv]

New Fist of the North Star anime to celebrate the franchise's 40th Anniversary.