Title character in the anime/manga series Bishoujo Senshi Sailor Moon. Originally the princess of the Moon Kingdom during the Silver Millennium a thousand years ago, she was killed when the forces of the Dark Kingdom destroyed her home. Through the power of Queen Serenity and the Ginzuishou, she was reborn in the twentieth century as Tsukino Usagi.

When the Dark Kingdom rose again, talking cat Luna (put in suspended animation when the moon kingdom fell) sought a champion to find the reborn princess and reassemble the Sailor Senshi. She found her champion in Usagi. Not realizing Usagi was herself the lost princess, she gave her a magical brooch that allowed her to transform into the pretty sailor-suited soldier for love and justice, Sailor Moon.

Sailor Moon's powers evolved over the five years the show was on the air, as did her personality. Originally a whining, clumsy, cowardly crybaby, she gained a tremendous inner strength and a powerful empathy for others...though she stayed clumsy. Her destructive powers faded into the background and she was portrayed more often as a redeemer figure, often sacrificing herself to save others and heal those who'd been turned to the side of evil.

Under certain circumstances she transforms into Princess Serenity. Her destiny is to become Neo-Queen Serenity, ruler of Crystal Tokyo. She now wields the Ginzuishou crystal.

I think hackwrench's identification of the Senshi with Chaos falls apart in two ways: the show stresses again and again and AGAIN the importance of teamwork over individual initiative (the bad guys fail because they can't work together) and at the end of the final season, Sailor Moon fights Chaos personified.