Lillian worked as a physician in Metropolis when she met billionaire Lionel Luthor. They married and Lillian gave birth to a son, Lex. Sometime after their son was born, Lionel started having an affair, which Lillian discovered when she surprised him with his mistress on a business trip. Wanting to rebuild things with his wife, Lionel sent away his pregnant lover and paid her to keep quiet about the affair.Four years later, the woman died and Lionel decided to adopt his illegitimate daughter, Lena, despite Lillian's protests.
Over the next few years, Lillian always favored her biological son over her adoptive daughter, as she considered Lex a genius and Lena not even a "real Luthor". Lillian claimed she did so because Lionel felt guilty seeing his beloved wife together with the child born of his affair, though this was clearly a lie. Despite their distant relationship though, Lena would acknowledge that Lillian did care for the former in some way and that there were "some good times".
Leader of Cadmus
After Lex was sentenced to 37 life terms in prison, Lillian loses contact with Lena after Lex's trial. Infuriated by her son's imprisonment and the humiliation caused to her family by Superman, she took over Project Cadmus, a secret lab that studied aliens, and severed its relationship with the government so she could use it for her personal vendetta against aliens of all kinds.
When John Corben was shot by Lena and left near death, Lillian took him to Cadmus and, as he regained consciousness, she told him that she could kill him with one click but also make him survive, John agreed, and Lillian injected liquid kryptonite in his veins causing his eyes to cloud over. The woman says that now it will be called "Metallo". After Metallo woke up he was struck by his newfound power and asked the woman who she was, to which she replied: "merely a Doctor". She then introduced him to Cadmus and explained their anti-alien mission, which he hastily sympathized with. After that, she gives him the mission to kill Superman and Supergirl. Later, despite the resistance of one of her subordinates, she ordered to turn him into another cyborg.
Lillian Luthor supplied whit alien weapon to Chet Miner's gang to alarm public opinion, spreading fear and discontent over the population. The next evening Miner called the woman and told her that, as people are afraid of these weapons, he had fulfilled his part of the bargain and his next move would be to attack Lena Luthor's charity evening to make money. However, she warned him that if they attack Lena, she would not support them. After Miner was arrested, he started to tell Detective Maggie Sawyer who gave them the weapons but, suddenly, he heard Lillian's voice inside his head, his ears began to bleed and he fell dead to the ground alongside the other two gang members.
Capturing Mon-El and SupergirlA few days later a bunch of Lillian's agents captured Mon-El and delivered him to a hidden base of Cadmus, putting him in a cage. Later, she told Supergirl at a special frequency that they have Mon-El and promised to kill him if she did not come. When Supergirl arrived in Cadmus, she met the real Hank Henshaw, revived as a cyborg, who was able to overcome her and imprison her in the cell next to that of Mon-El. Later Lillian revealed herself to Supergirl and threatened to kill Mon-El, if she does not deprive herself of solar energy with the help of a special device; Supergirl was forced to agree, then Lillian slapped her and took her blood before sending her back to the cells, not bothering she and Mon-El later managed to escape thanks to Jeremiah Danvers.
After having sent Hank to stole a sample of the Medusa virus from the Fortress of Solitude, Lillian began releasing it to kill all the aliens in National City. Later Lena contacted her and said she wanted to join forces with her to release the deadly virus on Earth to wipe out all alien life. However, Lena had no intention of releasing the virus; she rendered it inert via a critical ingredient, and alerted the police about her mother's crimes. Lillian only realized she'd been double-crossed when the missile carrying the virus exploded, sending only red rain falling on National City. Before she could react, the police swarmed in and arrested Lillian for attempted mass murder and other Cadmus-related crimes.
Freedom and ExodusLillian had her medical license revoked and her trial was impending. She received a visit from her daughter Lena, who she told she forgave her for testifying against her, though Lena told her that she wasn't buying it. Lillian then revealed that Lena was indeed a Luthor as Lionel was her father as he had an affair with her mother. She told Lena that the reason that they were always estranged was because her father didn't want her anywhere near her so she devoted her time to Lex instead. At her trial, Metallo managed to get a new Kryptonite heart which he used to free them both and draw Supergirl back and keep her from stopping them. When Lena was arrested for being a suspect in aiding in their escape, she sent Metallo to break her out of prison. Lena wasn't happy that she was broken out as it made her look guilty when she wasn't but Lillian told her that she had no where to go now. She told Lena that joining her and Cadmus was now her only option. They went to one of Lex's vaults where he had an anti-alien arsenal and that the only way to open it was with Luthor DNA, meaning Lena. Lena was angry with her as this was the real reason that they had broken her from prison but the vault was opened. Lillian was happy to see all of the things Lex had collected but was shocked to see that there was a mystery item there that Lex had completed. Supergirl arrived and Lillian had Metallo attack her though she tried to downplay her warnings that Metallo's new Kryptonite heart was unstable. However, when it seemed she was right, she and Hank Henshaw went and evacuated the bunker by a helicopter before Metallo exploded.
After having instructed Jeremiah Danvers to pretend to be rescued in order to infiltrate the D.E.O. and hand her the registration list of all the aliens living in the country, Lillian awaits him at a particular point and, after avoiding a vain attempt to capture by Supergirl and Alex Danvers, she travels with him and Henshaw in a secret facility of Cadmus from where they intended to launch their final plan.
Lillian had begun the next stage of Operation Exodus. They were rounding up all the Aliens that were registered in the country and were going to load them up into a space frigate that would jump into hyperspace and take all the aliens to a world all the way across the universe. Jeremiah told his daughter Alex that originally Lillian wanted to kill them all but he persuaded her to send them off instead. Lillian's mole that was posing as Lena's assistant warned her that her daughter was on to her so she ordered to have Lena halted. When Kara Danvers managed to post an article online that exposed their entire plan, she was forced to begin the launch early. Alex Danvers warned her that she had planted explosives all over the facility and would detonate them if she didn't halt the launch. At first, she thought Alex was bluffing until he detonated two of them. Lillian told her that she wouldn't stop it so Alex detonated them and then ran to stop the launch from the inside. Jeremiah then turned on her so she had Hank Henshaw take care of him before she fled. The plot was then foiled when Supergirl managed to keep the frigate from getting out of the atmosphere and making the hyperspace jump.
Return and arrest
One year later, after learning that Lena was poisoned by Morgan Edge, Lillian returns and tries to kill him with a drone, in retaliation. When Supergirl arrives, Lillian uses her drone to have a suit armor. She is finally defeated by Mon-El and Winn Schott and sent in jail, one more time.
Lillian is shown to be very much like her son, Lex Luthor; cold, self-righteous, unstable and delusional in her views. Blaming Superman for her son's imprisonment, while completely in denial of the horrific actions Lex performed of his own choices, Lillian came to develop a radically-driven disdain for aliens of all kinds. She views extraterrestrials as a poison to Earth, beings who are subtly taking control of the planet by making humans worship them, and is determined to purge the world of them. Lillian went as far as to round up all the aliens in the country to force them back into space (an alternative suggested by Jeremiah as Lillian initially wanted to kill all the aliens), despite the fact that many of them were just harmless refugees seeking shelter from dangers at home.
Lillian is shown to be rather hypocritical, willing to kill innocent bystanders, the very people who she claims to be trying to save, in her personal vendetta. While arrogant in her views and believing herself to be the true savior of the planet, Lillian is a very shrewd and cunning woman. Able to anticipate how her enemies will act, she is always several steps ahead and can manipulate their actions.
Even outside her blind hatred of aliens, Lillian is shown to be very opinionated and distant. During her entire adoption of her stepdaughter, Lena Luthor, Lillian made little effort in trying to connect with Lena, not completely agreeing with her husband Lionel's decision to adopt the child, preferring to focus her time on teaching Lex. Ultimately, she at most saw Lena as merely a good learning tool for her only blood-related child. Even in Lena's adulthood, Lillian's relationship with her was mostly professional, wanting to make sure Lena would keep the Luthor name in high regards.
However, Lillian's disdain for aliens greatly outweighed her strained relationship with Lena, as she is determined to "protect" her from Supergirl and the likes. To which, Lillian views have also made her short-sighted. Between her desire to exterminate all aliens and ensure that the people close to her live up to her high standards, it becomes much easier to deceive and manipulate her; when Lena apparently joined forces with her to release the Medusa virus, Lillian blindly let Lena move about freely, allowing the latter to double-cross her by sabotaging the virus and leading the police to their location.
Lillian is also a manipulative liar and as shown above, she is not above being selfish with her adoptive daughter or even using Lena for her own ends. When Lillian revealed that her husband is Lena's biological father, she claimed that Lionel never allowed them to form a close relationship because he couldn't stand seeing his wife together with the child born of his affair. However, this was simply a bid to get Lena to lower her guard and trust Lillian, who wanted to frame and take Lena on the run to get access to Lex's technology, not caring that her actions could damage Lena's reputation. In reality, Lillian has always been cold to Lena because to her, she is a living reminder of Lionel's affair.
Lillian seemed unable to understand the concept of love regarding her enemies and only seeks to exploit it. She didn't think Lena's friendship with Supergirl meant anything, believing she would give up on Lena once the latter was framed for a crime. Even when Supergirl proved this wrong, Lillian still felt that Lena would hate the superheroine if she learned the latter's secret identity as Kara Danvers. Lillian even blackmailed Jeremiah Danvers into infiltrating the D.E.O. by using the trust his family and friends had in him, not expecting the fact that Jeremiah's love for them would make him double-cross her. These traits of Lillian's may have stemmed out of bitterness over her husband's infidelity.
However, Lillian did make a genuine effort to build a relationship with Lena later on. When Lena was abducted by Rhea, Lillian resorted to teaming up with Supergirl to save her adoptive daughter, but was not above betraying her once Lena was safe (though this failed). Lillian even apologized to Lena for her past actions, genuinely remorseful of her failure to be a good mother and put her daughter first. She remained confident in Lena's intellect and never told her Supergirl was Kara Danvers because she was sure Lena would figure it out one day. Lillian even encouraged Lena to reconfigure Lex's invention to rid the Earth of the Daxamites, stating that she was even more brilliant than him.
When Morgan Edge attempted to frame and kill Lena, Lillian returned to National City to kill Edge in retribution and even showed up to do so in person when her drones failed, despite Lena and Supergirl's protests in favor of doing it the legal way. When Lillian was arrested, she showed a softer side to Lena as well as a dry sense of humor, asking to be shown the "right" way when Lena visits her in prison, provided she does so before Lillian breaks out.
During her time in prison, Lillian is shown to have apparently mellowed down, crediting the fact when Reign nearly terraformed the earth, she did not want to die or be alone and realized she needed to change. Lillian appears to have begun making amends with Lena, as the two often play chess together. Lillian even gave Supergirl the location to every Cadmus facility to track down Mercy and Otis Graves. When Lillian realized Lena tricked her into giving information on Bruno Mannheim to save James Olsen, she was impressed by this and knocked down her king piece (symbolizing her defeat).
Powers and abilities
- Lexosuit application: Lillian is masterful in using Lex Luthor's Lexosuit battle armor to suit her needs and protect herself against Kryptonian-level threats.
- Genius-level intellect/Expert scientist/Leader: As a scientist, Lillian has a genius level intellect, as she was able to create cyborgs synthesizing kryptonite as a weapon and even to reproduce the Medusa virus from a sample.
- Indomitable will: A driven and determined person, Lillian is nearly fearless and almost always calm in every situation, as evidenced by not being intimidated even when menaced by a gang of men armed with alien technology or at the time of her arrest.
Behind the scenes
- In the DC comics, Lex Luthor's mother is named Arlene Luthor. In later incarnations, her name was changed to "Leticia", even though in most of her appearances she remains unnamed.