Momochi Zabuza

Momochi Zabuza is known as the devil of the mist. He is infamous for killing over 100 ninjas to pass the final test of being a shinobi. He joined the Hidden Mist's ANBU but his heart for killing never left him, eventually he plotted to overthrow the Kage. However, his plan was thrawted thus causing him to flee from the Hidden Mist Village, becoming a missing-nin.

Being a Hidden - Mist ninja, most of his Jutsus are water-based and being a Jounin, he is highly skilled. He wields his blade with ease, even though it is very heavy and long. While being in ANBU, he stumbled upon Haku and upon knowing that he possess an Advanced Bloodline, he took Haku under his wind. However he only treated Haku as a tool for him to be utilised. He taught Haku all the skills he known and eventually Haku became a hunter-nin.

One of Zabuza favourtie Jutsu is Hidden Mist no Jutsu which he frequently uses to hide himself from the enemy before attacking. While locked in battle with Kakashi, he manage to gain the upper hand by trapping Kakashi in his specialty Suirou no Jutsu. However, it was broken by Naruto thus Kakashi took advantage and used Chidori. Just before Chidori hit Zabuza, Haku intervened and took the blow for him, killing Haku instantly and protecting Zabuza. At first Zabuza just brushed off Haku's death but after hearing Naruto's lecturing, he realised how Haku treated him as a person willing to die off, Zabuza then picked up a Kunai with his mouth killing Gatoh. Then finally before he died, he asked to be placed beside Haku.

Even though Zabuza was known as the devil of the mist, at the end, from his emotions towards Haku, it shows that he is not that cold after all.