|First Anime Appearance:||Sailor Moon Eternal|
|First Manga Appearance:||Act 40 Yume 2 Mercury Dream|
|First PGSM Appearance:||N/A|
Guardian Mercury was the Sailor Power Guardian of Sailor Mercury. She referred to herself as Sailor Mercury's other self.
| Guardian Mercury|
Guardian Mercury gave Ami Mizuno the Mercury Crystal. She reappeared again in Act 48, directing Princess Mercury to ask for power from Mariner Castle.