The HAND is a evil organization running by evil masters & ninjas in shadows of New York City.
In Comics -
The Hand is an order of evil mystical ninjas who are heavily involved in organized crime and mercenary activities such as assassination plots. The Hand covets power above all other objectives. They are primarily based in Japan, but operate internationally. They were founded in 1588 as a secret society of Japanese nationalist samurai but were soon co-opted by the Snakeroot, an ancient ninja clan which serves a primordial demon known only as "The Beast of the Hand".
The Hand is an order of evil mystical ninjas who are heavily involved in organized crime and mercenary activities such as assassination plots. The Hand covets power above all other objectives. They are primarily based in Japan, but operate internationally. They were founded in 1588 as a secret society of Japanese nationalist samurai but were soon co-opted by the Snakeroot, an ancient ninja clan which serves a primordial demon known only as "The Beast of the Hand".
Members of the Hand are practitioners of powerful occult magic and can murder a person and bring that person back to life as a servant of the Hand, but a few are known to have reversed this programming. The Hand's most dangerous adversary is The Chaste, a band of warriors once led by Stick, the blind martial arts master and mentor of Matt Murdock, who grew to become the costumed crime-fighter Daredevil
In MCU (Netflix version) - Hand, was an ancient and powerful ninja clan with the ultimate goal to gain immortality. The Hand originated in K'un-Lun, when the five founders were banished from the city and have since lived on in the shadows for centuries, promoting their goal through wars and influence on powerful people. When the Hand came to New York City, the branch leader Nobu Yoshioka used Wilson Fisk in order to bring to the city Black Sky. However, his plan was interrupted by the vigilante Daredevil, and eventually they had to stop their operation after Yoshioka's death. By the power of resurrection the Hand had obtained, Yoshioka returned to lead the Hand in New York City in order to find a new Black Sky for their war against the Chaste. Elektra was the new Black Sky, but she refused to join them and after the Attack on the Hand, both she and Yoshioka were dead.
Madame Gao, another branch leader, continued her heroin distribution in the city with the help of her influence on Rand Enterprises. The return of Danny Rand, the new Iron Fist, caused total destruction of her operation and the resurface of Bakuto's branch, who was dedicated to turn Iron Fist to their side. His death by Davos did not stop the Hand from launching an assault on the city of K'un-Lun with the absence of the Iron Fist.
Alexandra Reid used the last of The Substance, their regenerative elixir, to bring back Elektra to serve the Hand as their Black Sky. In order to find more of the Substance, the five leaders gathered once more in New York City and tried to catch Iron Fist so he would open the gates for the substance. However, the Defenders were formed in order to stop them from destroying the city. As the Hand reached for the substance, Elektra killed Reid and led the Hand for her own purposes, only to lead them to their doom when the Defenders buried the rest of the leaders under the ground.