Using the Geass and his genius-level intellect, Lelouch becomes the leader of the resistance movement known as The Black Knights under his alter ego Zero (ゼロ) to destroy the Holy Britannian Empire, an imperial monarchy that has been conquering various countries under the control of his father.

Besides Code Geass, Lelouch has appeared in multiple related adaptations; in Nightmare of Nunnally, the protagonist has become a superpowered human combined with C.C.

; in Akito the Exiled, he is a strategist brainwashed by his father as a supporting character; and in Code Geass: Lelouch of the Re;surrection (2019), he is leading his forces in an alternate sequel to the original television series.

Inspired by the tokusatsu series Kamen Rider, director Gorō Taniguchi created Lelouch with the idea of having an evil protagonist who would appeal to the audience.

Lelouch was designed by a group of manga artists called Clamp, who aimed to create a stylish and visually appealing character.

The basic idea for the plot of Code Geass consisted of a "hero" who led a secret organization, which later developed into a conflict between two characters with different values and who belonged to the same military unit, who eventually became Lelouch and his best friend Suzaku Kururugi.

Director Gorō Taniguchi wanted Lelouch's actions in the television series to have a major impact on the cast, later resulting in the creation of the movie to explore it further.

[2] Writer Ichirō Ōkouchi says that while Lelouch is important to bring peace to the world at the cost of his life, Suzaku and several other characters have to remain alive to live up to his legacy.

Just like Lelouch, the boss of Shocker begins by creating an evil organization, but by sheer bad luck, his childhood friend becomes Kamen Rider and comes to destroy him.

Taniguchi asked designers Takahiro Kimura, Yuriko Chiba, and Kazuya Murata for help when animating the character, most notably whenever Lelouch moves his hands and does poses while talking.

[7] During the early planning stages for Lelouch's alter ego, "Zero", Clamp wanted to create a mask never witnessed prior in any Sunrise series.

[24] With his new power, Lelouch begins his rebellion against the Britannian Empire, starting by killing his half-brother, Clovis la Britannia, after extracting information about the murder of his mother.

[26][27] The turning point in his rebellion comes when his half-sister, Euphemia li Britannia, declares the region under Mount Fuji the Special Administrative Zone of Japan, giving the Japanese people their name and country back.

[28] Lelouch reluctantly kills her and uses the massacre as an excuse to spark the Black Rebellion, in which he declares Japan to be an independent nation and leads an attack on the Tokyo Settlement.

[29] The attack goes well at first, but when Lelouch learns that Nunnally has been kidnapped, he abandons the battle, leaving his forces helpless against the better-organized Britannian military.

[33] The Black Knights escape to the Chinese Federation, where Lelouch begins forging an alliance with the other world powers to create a force that rivals Britannia.

Schneizel then convinces the Black Knights to betray him, with a despondent Lelouch willing to be killed by his former comrades, until Rolo sacrifices his life to save him.

One month later, Lelouch usurps the Britannian throne and appoints Suzaku as his knight to set the stage for their ultimate plan, the Zero Requiem.

[35][36] This brings him into conflict with Schneizel, who has Nunnally in his custody and commands the Damocles (a floating fortress that he intends to place into a position that would allow him to fire nuclear weapons worldwide), and the Black Knights.

Upon arriving in St. Petersburg, Kingsley proudly declares that the Emperor has placed him in charge of all the Eastern front operational planning for Britannia's military.

[47] After several fights against Britannia, Zero orders the Black Knights to side with the army to defeat the Emperor, as Euphemia is due to take over the empire.

Anime News Network's Carl Kimlinger stated that Lelouch "is hard to like" because of his narcissistic personality, but noted that his bonds with Nunnally and his friends make up for that.

[65] A mostly positive response was given by Danielle Van Gorder from Mania Entertainment due to Lelouch's differences from most anime protagonists and how his double life as 'Zero' and as a student is shown across the series.

[66] IGN compared Lelouch with Light Yagami from the Death Note series due to his double life and his questionable methods, respectively.

[67] Also from IGN, Ramsey Isler found Lelouch's double life trait to be rather comical, as after the short prologue of his role as Zero in an episode, he is seen doing homework at school for being absent from classes.

[69][70] The book Language Arts in Asia 2: English and Chinese Through Literature, Drama and Popular Culture claims that the staff behind the anime took a bold approach to titling the series' first episode "The Day a New Demon was Born", as its first scene follows Lelouch as a child who wants to destroy the Empire of Britannia, and when using the power of the Geass as a teenager, he uses this to protect himself by ordering all Britannian soldiers to kill each other.

[75] Gia Manry from the same site listed Suzaku and him as the third-best "frenemies" in anime due to how their friendship falls apart as a result of their rivalry.

[76] The rivalry was praised by Nicole Soto Rodríguez due to how dangerous the methods employed by Suzaku and Lelouch are and how both come across as hypocrites when defending each other as the narrative explores philosophies involving them.

[77] The Fandom Post noted that Suzaku and Lelouch's relationship might attract female viewers, so he recommended an anthology manga to them, praising the multiple designs presented commonly seen in the yaoi genre.

[81] The Fandom Post commented that when reviving, with it being the thing he was looking forward to the most, Lelouch retains his old traits, such as his love interests and his bond with Suzaku.