The Mizukage (水影; Literally meaning "Water Shadow") is the leader of Kirigakure. As far, there have been 5 Mizukage, though only two have been mentioned. The Mizukage has full authority with political, economical and military issues concerning Kirigakure. The Mizukage's building is the widest and largest landmark in Kirigakure, bearing the kanji for Mizu (水; Literally meaning "Water") on it.
List of Mizukage
Yagura (やぐら, Yagura) was the jinchūriki of Isobu, the Three-Tails and the Fourth Mizukage (四代目水影, Yondaime Mizukage; Literally meaning "Fourth Water Shadow") of Kirigakure. At some point in time, he was controlled by Tobi, literally making him the "Fourth Mizukage" . It is noted that Kirigakure's title; "Village of the Bloody Mist" started before Yagura's era.
Mei Terumī (照美メイ, Terumī Mei) is the Fifth Mizukage (五代目水影, Godaime Mizukage; Literally meaning "Fifth Water Shadow") of Kirigakure. She became Mizukage towards the start of the manga, after the dreadful reign of Yagura ended. She has worked tirelessly to recreate diplomatic relations with other villages, as well as reform internal policies.