Happy Birthday: Night Girl
Lydda Jath was born on the planet Kathoon, a world that lives in permanent darkness. Her scientist father found a way to give her super-strength but didn’t realize it would only work at night or in deep shadows.
Lydda applied for the Legion of Super-Heroes but was turned down because they felt her power’s limitation made it impractical. She met Brek Bannin, Polar Boy, at the tryouts and together they formed the Legion of Substitute Heroes.
After the events of Infinite Crisis, it appears that future history has been rewritten and Lydda has become a member of the Legion of Super-Heroes instead.