Alexis Luthor was a character from the Legion of Superheroes and originally a friend of Superboy, though she was always spoiled and selfish.
She would only turn antagonistic after Superboy began to try and break ties with her in order to help the Legion deal with supervillains, unwilling to stand by and let Superboy be a hero Alexis decided to "get rid of the competition" by attacking the Legion with the aid of her hi-technology and even attempted to kill Superboy after he rejected her once again.
Yet in the explosion caused by her failed attempts to damage Superboy her hair fell off (a subtle reference to the Golden Age origin of Lex Luthor's baldness) and she blamed Superboy for her humiliation - as well as her subsequent imprisonment for her crimes.
When last Alexis was seen she was still in prison and clearly still holding a grudge against Superboy, despite him having done everything he could to reason with her. Alexis was supposed to have a role in the second season working for Imperiex alongside Lightning Lord, ultimately redeeming herself by betraying him and helping to defeat him, earning her a high political position. However, the WB Network wanted fewer female characters on the show, and as a result this plan was scrapped.
In the Comics
In Earth-9 of Multiversaity Alexis appears as the daughter of Luthor and lover of Damien Wayne.
|Legion of Super-Heroes Villains|
Alexis Luthor| Blight | Brainiac | Composite Superman | Computo | Controllers | Cosmic King | Dark Circle | Darkseid | Dominators | Emerald Empress | Evillo | Fatal Five | Glorith | Grimbor | Hunter | Infinite Man | Justice League of Earth | Khunds | Legion of Super-Villains | Leland McCauley | Lightning Lord | Mano | Mordru | Nemesis Kid | Ol-Vir | Omega | Persuader | Pulsar Stragrave | Ra's al Ghul | Roxxas | Saturn Queen | Sklarian Raiders | Starfinger | Sun-Eater | Superboy-Prime | Taurus Gang | Tharok | Time Trapper | Tyr | Universo | Validus | Vandal Savage | White Triangle