[1] Night Girl is a native of the planet Kathoon,[2] a world which is in perpetual darkness and heated by an internal power source.

In pre-Zero Hour continuity, she unsuccessfully tried out for the Legion of Super-Heroes, who rejected her due to her situational and impractical abilities.

During the Five Year Gap, 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.

[5] In post-Zero Hour continuity, Night Girl made two 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.

Night Girl has superhuman strength and durability equivalent to that of Superboy or Mon-El, but only in darkness or deep shadow.