Meizu

and with his twin brother Gōzu were chūnin of Kirigakure before defecting and becoming mercenaries alongside Zabuza Momochi.

Background
He and his brother fled the village with Zabuza when he failed in his attempt to kill the Mizukage, and thereafter began working for him as assassins.

Personality
In sharp contrast to his brother, Meizu is described as having a short temper and is extremely violent while torturing his foes. He has also been described as a hooligan.

Appearance
Meizu had shoulder-length, wild dark-brown hair and dark eyes. He wears a rebreather that covers the lower half of his face and a large, clawed, poisonous gauntlet on his left arm which had a chain coming out of it that had the other end attached to his brother's own gauntlet. He wore a camouflage suit with bandages around his waist, dark-coloured, knee-length sandals and several pouches around his waist. His Kirigakure forehead protector had two horns on it.

Abilites
Gōzu and Meizu are a paragon of coordination attacking. Meizu's large metal gauntlets house a retractable shuriken chain running between the two of them, which they can use to bind an enemy and then slice them to pieces. In the event that the shuriken chain is neutralised, Gōzu also has a release mechanism to free him from Meizu for individual attacks. He uses the sharp, poisoned claws on his gauntlet to shred his foes. Meizu was also skilled in stealth, capable of hiding right outside the gates of Konoha without being noticed.

Nature Transformation
Meizu and Gōzu have proven skilled in Water Release being capable of appearing out of puddles, hiding in them when needed.

Prologue — Land of Waves
At the start of the series Zabuza sends them to kill Tazuna. Using the Water Release: Hiding in Water Technique to surprise Team 7. With Gōzu immediately launching his brother in front of him the pair are seemingly able to kill Kakashi with ease. As they move on to attack Naruto Uzumaki, they are stopped by Sasuke Uchiha who breaks the chain connecting the two brothers. Still intent on killing them, the brother separate and attack the team. They are however stopped by Kakashi Hatake, and it is revealed that he had used the Body Replacement Technique to escape their first attack. He later ties them to a tree so that they can be taken into custody.

Trivia

 * Meizu's name is written with the kanji for "dark" (冥) and "head" (頭), indicating his mindset overshadowed by emotions, in contrast to his brother's more rational way of thinking.
 * According to the databook(s):
 * Meizu has completed 278 official missions in total: 68 D-rank, 167 C-rank, 43 B-rank, 0 A-rank, 0 S-rank.
 * In Japanese mythology Gōzu and Meizu are fearsome guardians of the Underworld known more commonly as "Ox-Head" and "Horse-Face".