Shadow Lass is Tasmia Mallor, a member of the Legion of Super-Heroes in the 30th Century. Born on the planet Talok VIII, she was given the ability to manipulate darkness. The Talokites choose a different shadow champion in every generation. Her cousin Grev is Shadow Kid, her 20th Century ancestors in L.E.G.I.O.N. are Lydea Mallor and Lyrissa Mallor. Her longest romantic partner is Mon-El.
In Reboot Legion continuity, a colder and more aggressive Tasmia uses the name Umbra. In Prime Legion continuity, she uses the name Shadow Lass again. This version dates Ultra Boy. Shadow Lass was created by Jim Shooter and Curt Swan, first appearing in Adventure Comics #365. (1968)