Queen Serenity is the Moon Goddess Serene and former Queen of the Silver Millennium. She spent her reign protecting the Silver Crystal and raising her daughter, Princess Serenity, to eventually inherit the throne. This peace was fragile—Earth and the Moon Kingdom were at war, driven by Earth's jealousy of the Moon's prosperity. Prince Endymion of Earth became an exception, siding with the Moon partly out of love for Princess Serenity and partly out of moral conviction.
Everything changed when Queen Metallia and the Dark Kingdom invaded. The attack was catastrophic, wiping out nearly everyone. Queen Serenity survived along with the advisors Luna and Artemis, but her daughter and all her subjects were dead. Devastated, she poured the full power of the Silver Crystal into two acts: sealing away Metallia and sending the dead forward in time to be reborn in a future age. The effort killed her. Her spirit lingered on the Moon, watching over Earth until her daughter's reincarnation was born.
In the anime, Queen Serenity shows up sparingly. Near the end of the first series, she appears to the Sailor Senshi as a ghostly vision, explaining the Moon Kingdom's history. She reappears early in the R series to restore the Silver Crystal to Usagi and give her a new transformation brooch, then vanishes from the story.
The manga gives her more weight. A holographic image replaces the sprite, and after Usagi defeats Metallia, Queen Serenity offers her the throne—an offer Usagi refuses. The Super S arc really expands her backstory: Usagi recovers childhood memories revealing that Queen Neherenia was Queen Serenity's sister. Both originally came from elsewhere in the galaxy before settling on the Moon. When Neherenia tried to recruit Serenity to evil plans, Serenity refused, prompting Neherenia to curse the infant Princess and trap herself in a mirror after her defeat.
By the time Princess Serenity was four or five, nightmares from the curse plagued her. In that moment, Queen Serenity offers the advice that becomes the series' central philosophy: keeping the light in your heart strong enough to overcome darkness.
Content compiled by AnimeList.moe from publicly available sources.
