Night Girl is a native of the planet Kathoon,[1] a world which is in perpetual darkness, heated by an internal power source. Lydda has super strength and invulnerability, given to her by her scientist father, but only at night or in deep shadow. Her powers were negated by the presence of ultra-violet energy, or direct sunlight from a yellow sun like ours.
In pre-Zero Hour continuity, she unsuccessfully tried out for the Legion of Super-Heroes who rejected her[2] on the basis that a power that only worked in darkness was impractical. After meeting fellow Legion reject Polar Boy, she became one of the founding members of the Legion of Substitute Heroes.
While having powers with such a drastic limitation reduced her effectiveness as a superhero, she became quite skilled at martial arts. She discovered the best Legionnaire for her to work with was Shadow Lass She had a crush on Cosmic Boy, which was her motivation for leaving Kathoon and trying out for the Legion in the first place. She alone among the Subs avoided the bumbling comedic stigma which plagued her teammates. During the Five Year Gap tales, she and Rokk married and eventually had a son Pol (named for Cosmic Boy's fallen brother, Legionnaire Magnetic Kid) and resettled back on her homeworld as her husband reformed the Legion. In the stories of the Adult Legion, Night Girl (now Night Woman) and Cosmic Man are married and have a child. In post-Zero Hour continuity Night Girl made two very brief appearances, first in Legionnaires #43 as she was rejected at a try-out once again and joined the Legion of Substitute Heroes once more.
In a nod to the previous continuity she noted that, had she been aware Cosmic Boy was on a secret mission, she might not have even made the attempt. She was seen in one panel in Legionnaires #49 as she and Polar Boy talked about how the Substitute Legion had a long way to go until they were ready to take on a mission.
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