The Brain is a medical and scientific evil genius, and one of the leaders of the Light, designated L-6. He is usually accompanied by his loyal sidekick, Monsieur Mallah, who is a gorilla with roughly human-level intelligence.
The Brain is a superb scientist, as he was capable of reverse-engineering the Kobra-Venom and used it on Indian fauna to enhance their strength. He also evinces some sadistic traits, mainly evidenced when he attempted to surgically remove Captain Marvel's brain while he was still alive. The Brain has an idiosyncratic speech pattern: he speaks English with a very thick French accent, and often code-switches, throwing French words in the mix. He does this because he detests speaking English.
The Brain is essentially a disembodied brain kept alive in a mechanical dome. Before that, he took the appearance of a scraggy, tall man with unkempt black hair and black eyes.
His new robot body is equipped with retractable mechanical appendages that allow him to handle objects, as well as weapons.
Somewhere between 2006 and 2007, the Brain joined the ranks of the Light.
The man who came to be known as "the Brain" was one of the unnamed leaders of a group of scientists that settled in Bwunda, in 2008, to conduct experiments on the indigenous gorillas. After implanting the female leader's brain into the body of an albino gorilla, thus creating the Ultra-Humanite, he had his own brain removed and stored in a robotic container.
The scientists built a compound of laboratories, which they named "Gorilla City" as a display of sadistic mockery, and proceeded to enslave an entire troop of gorillas, save for one who managed to elude them. They subdued the gorillas with inhibitor collars and enhanced them with brain procedures and Kobra-Venom. In order to ensure the gorilla's cooperation, the scientists held their children hostage.
When Aqualad, Robin and Kid Flash broke into Cadmus, Mark Desmond requested an audience with the Board of Directors, and briefed them on the incident, also informing them that the three heroes had been apprehended. L-3 ordered Desmond to clone them and L-1 told him to dispose of the originals. This course of action ultimately failed and the boys broke out and took Superboy with them. L-1 dismissed the severity of the ordeal and remarked that the loss of the clone could be played to the Light's advantage.
When Sportsmaster reported the loss of the batch of Kobra-Venom due to the young heroes' interference in Santa Prisca, the Brain conjectured that maybe they could reverse engineer the only salvaged vial. He then pointed out that this was not the first time the young heroes had thwarted their operations, recalling the breaking and entering of Cadmus and the destruction of Mister Twister.
Batman had become suspicious of the attacks purportedly executed by intelligent animals, and sent the Team to investigate, with Captain Marvel tagging along. After Mallah and a reluctant Tawny captured Marvel, the Brain tried to dissect Marvel's brain, curious of the affect his powers had on it. However, Tawny turned on the Brain, saving Marvel, and the Team eventually came to the rescue. Outnumbered, the Brain activated a strange device, turning out the lights in the room and disappeared with Mallah.
Brain ran a Kobra-Venom operation in Bwunda, focusing on enhancing gorillas together with Ultra-Humanite. Just three days after their last encounter, he learned the Team was on his trail again. He suggested that Ultra-Humanite summon Gorilla Grodd to stop them.
Grodd and Solovar apprehended the Team, except for Miss Martian, to the hideout. They could not find Miss Martian and did not bring Wolf. Ultra-Humanite explained that Brain only asked for the Team and that they could not understand that he also wanted Wolf. Brain gave them infrared goggles to find Miss Martian and Wolf. He send them out and told them they could not return until they found them.
With the captured Team members shackled, disarmed and apparently unconscious, the Brain proposed several possible experiments to perform on them. Grodd brought in Wolf, shortly after which Robin escaped. After Robin detonated smoke pellets and freed his teammates, Brain called for reinforcements. When Solovar arrived with Miss Martian as his "captive", Brain threatened to have her killed if the Team did not stand down. The Team and their gorilla allies attacked, knowing M'gann was in no danger. Artemis snared the Brain with a foam arrow, and Robin electrocuted him with a batarang. Brain was fascinated to discover the gorillas had developed telepathy, but had to focus on the losing battle. He activated the base's self-destruct, forcing everyone to flee.
After the arrest of the Injustice League, the Brain was present with the other members of the Light to hear Vandal Savage's view of the Kobra-Venom plant test and the heroes believing they had exposed the Secret Society.
Brain was present with the rest of the Light as Sportsmaster aired his grievances regarding the death of Artemis and the revelation that Deathstroke has replaced Sportsmaster as the Light's new enforcer.
Brain was among the Light's representatives at a summit with the Reach. During the summit, the Light learned that Aqualad and Artemis had infiltrated their ranks, then Aqualad revealed the Light's real agenda to the Reach and that the Team had set both parties up for an ambush. Brain sealed off the exits to the cave and several League of Shadows agents arrived, but some of them were Team members in disguise. Brain targeted Kid Flash and Impulse with his weapons, but the two ran circles around him and Impulse eventually disarmed Brain. He, Black Manta, Monsieur Mallah and the Reach ambassador were ultimately taken into custody by the Team.
In the comics, the Brain is the leader of the Brotherhood of Evil, the archnemeses of the Doom Patrol and Teen Titans. He is aided by his loyal ally (and later lover) Monsieur Mallah. They were both killed by Gorilla Grodd during the "Salvation Run" event.
This marks the Brain's third animated appearance. He first appeared in Teen Titans, as the main villain in the last season, and appeared in several episodes of Batman: The Brave and the Bold.
↑In "Drop-Zone", L-6 was voiced by Nolan North, but he was a temporary choice to save money on voice actors (source). Corey Burton took over the role when the Brain was introduced in "Alpha Male".