Lillie is a major character in Pokémon Sun & Moon Versions. Formerly a member of the Aether Foundation, she fled with Cosmog to escape her mother's abusive and unethical behavior. She is the daughter of Lusamine and sister of Gladion, and becomes close friends with the player character (either Elio or Selene) over the course of the game.

Lillie's default outfit is styled to emulate the appearance of Nihilego, an Ultra Beast her mother is obsessed with.

Lillie is a human. Though she takes care of Cosmog, she does not become a Pokémon trainer until the end of the game.