Hoshigaki Kisame

A highly dangerous S-Ranked criminal, Kisame was an elite Jounin in Hidden Mist Village until he began to assassinate the local Mist feudal lords. Fleeing his village, Kisame then joined the Akatsuki Organization. Kisame was ordered by the leader of Akatsuki to partner with Uchiha Itachi and obtain the Kyuubi demon from within Naruto. The two S-Ranked criminals went to Leaf Village in search of Naruto. Sarutobi Asuma and Yuuhi Kurenai confronted the two, so the ninja began to battle. Kisame used his head-cleaver against Asuma and managed to surprise the Leaf Jounin with its shark skin scales. Kisame drew blood but Asuma was able to recover himself. When Maito Gai appeared, Itachi and Kisame fled.
Later Kisame and Itachi tracked Naruto down to a hotel outside of Leaf Village. They were about to capture Naruto when Sasuke and Jiraiya appeared. Seeing that it was not the right moment, the two Akatsuki members fled. Over the next few years, Kisame and Akatsuki would wait patiently to capture more demon vessels like Naruto.
When Akatsuki members Sasori and Deidara returned from Hidden Sand with the captured Gaara in tow, Itachi and Kisame were directed to delay the pursuing Leaf and Sand ninja. Kisame was eager to get a measure of revenge again Maito Gai who had gave him a hard kick years earlier. Kisame managed to capture Gai's former students in a water prison, allowing himself and Gai to duke it out one on one. Gai was forced to open his gates to avoid Kisame's water attacks. Gai pummeled Kisame and knocked him back to the earth. Gai then learned that the Kisame he fought was not really Kisame himself, but another who was sacrificed to become Kisame in appearance while Kisame himself could fight through him from afar. The delay plan worked, and Kisame and Itachi were able to give Akatsuki enough time to remove Shukaku from Gaara.