The Black Knights is a sub-organization within the Revolutionary Army, and acts as a public military force with the intent of planting the seeds of rebellion within the Empire through various means. It is led by "Zero."
First appearing in his world, Zero introduces the Black Knights to the world as an organization which protects those without power from those who have it. Under his leadership, the Black Knights grow in strength exponentially, becoming a force rivaling the Britannian army. At the end of the first season, Lelouch declares the formation of the United States of Japan, a nation of acceptance and tolerance where any and all can seek refuge.
Though Lelouch reorganizes the Black Knights to form a structured hierarchy and chain of command, the Black Knights rely heavily on his masterful strategies, unable to act effectively when he has not given them specific orders. During the Black Rebellion in the first season finale, the group falls apart when Lelouch suddenly takes leave. In the process, both senior knights, Yoshida and Inoue, along with Kizuna Kagesaki, are killed. Several key members are arrested by Britannia, while others go into hiding.
Despite their defeat, some of the Black Knights are active during the period between. One of their activities was when they attacked Ashford Academy by committing robbery in Japan during the school festival. Peace Mark, which is a terrorist deployed organization, began making its move to continually resist Britannia for the period of time until their return. Terrorist movements have occurred in other Areas as well only to increase Britannia's reign.
After having his memories restored in the second season, Lelouch works to form a larger alliance of nations known as the United States of Japan to fight Britannia. He rescues the key members and arranges the exile of the Black Knights from Japan for this purpose, making their new base of operations on an artificial island off the coast of China. He starts by returning control of the Chinese Federation to its Empress, making them his first ally.
With the formation of the United Federation of Nations, the Black Knights was contracted to serve it's military force as well a protector of all U.F.N. member states, in exchange for their continued funding, manpower, and support.
After the second battle of Tokyo, a Britannian envoy carrying Schneizel el Britannia lands on the Black Knights' flagship - Ikaruga. In a meeting with a majority of the Black Knights' core members, Schneizel reveals Zero's true identity and Geass as well as insinuating that Lelouch has used his Geass to make them nothing more than his pawns. This, along with Villetta and Ohgi's testimony further drives a wedge among the Black Knights. Following Ohgi's suggestion, the Black Knights decided to betray Lelouch in exchange for the liberation of Japan. Diethard convinces the others to announce that Zero died of injuries sustained in battle, as no one would believe the truth and they would be stripped of their positions if they tried to explain it. Kallen later takes the role temporarily.
Ohgi is forced to reveal the truth to Kaguya and Xingke when Lelouch causes a rebellion within the Emperor's forces. A month later, the Black Knights are stunned when Lelouch takes the Britannian throne for himself. After Lelouch conquered Japan and took the UFN leaders hostage, they allied themselves with Schneizel's forces to oppose Lelouch.
After the Black Knights were defeated by Lelouch, Suzaku took up the mantle of Zero. He proceeded to kill Lelouch in order to complete the Zero Requiem. Afterwards, Suzaku has become the new leader of the new incarnation of the Black Knights to lead peace and justice.
Akame ga Kill!
In the world of Akame ga Kill!, the Black Knights function as a sub-organization within the Revolutionary Army, and unlike Night Raid, they operate publicly. It's ranks are composed of civilians and soldiers who are disturbed or do not agree with the Empire, and even receive financial backing from various nobles who wish for the Empire to be changed. Like it's parallel counterpart, the Black Knights also function differently from terrorist organizations and the Revolutionary Army itself, as Akarui, it's founder, states that it will defend those without power. According to Akarui, the purpose of the Black Knights is to plant a seed of rebellion from within the Empire itself, as the military organization begins to gain fame and popularity towards the majority of the minor citizens, as well as few of the upper-class citizens.
In regards to the Black Knights, the Empire is naturally opposed to it, and view both the organization, and it's leader, as serious threats. Honest describes them as "cancer" which seeks to undermine his power, while Budo refers to them as a major threat to the Empire, though he also admits that he "respects" them to a certain degree. Esdeath herself wishes to engage them in combat, seeing them as the first real challenge she has seen in many years since the uprising several years ago.
- Akarui/Zero (Founder) - Leader
- Marx - Second-in-Command
- Seryu - Captain of Special Forces
The Black Knights, being a sub-organization like Night Raid, is funded by the Revolutionary Army, as well as several nobles who do not agree with the Empire.