Ami Mizuno (水野亜美, Mizuno Ami, renamed "Amy Anderson" or "Amy Mizuno" in some English adaptations), better known as Sailor Mercury (セーラーマーキュリー, Sērā Mākyurī) is a fictional character in the Sailor Moon manga series created by Naoko Takeuchi, a teenage Japanese schoolgirl, and a member of the Sailor Guardians, supernatural female fighters who protect the Solar System from evil.

Sailor Mercury is the first Sailor Guardian to be discovered by Sailor Moon. She serves as the "brains" of the group, as she is highly intelligent and can also use a supercomputer to collect useful information in battles. She possesses powers associated with water and ice.

Aside from the main body of the Sailor Moon series, Ami features in her own short story in the manga Ami's First Love. Originally published in volume fourteen of the manga, this was the only of three "Exam Battle" stories to be made into a special for the anime which makes her one of the most recognizable and popular characters in the series. A number of image songs mentioning Ami's character have been released as well, including the contents of three different 3-inch CD singles.