Lysithea can refer to a few different things:
Lysithea (alga), a genus of red algae in the family Bangiaceae Lysithea (moon), a moon of Jupiter Lysithea (mythology), a figure in Greek mythology Lysithea, a fictional spacecraft carrier in Voices of a Distant Star Lysithea von Ordelia, a fictional character from the video game Fire Emblem: Three Houses
See also Cosmopterix lysithea, a species of moth