Hoshigaki Kisame was introduced alongside Uchiha Itachi, as a fellow member of the dreaded Akatsuki. Not much is known about Kisame, other than his past affiliation with Momochi Zabuza in the Hidden Mist's Seven Legendary Swordsmen group. He has a freakish personality and an equally freakish shark-like appearance.
He has a terrifying sword he calls Samehada, which is basically a chakra-absorbing sword that cuts through his opponent's chakra by absorbing the chakra around it. The amount of chakra it can absorb is unclear, but seems to be unlimited. Kisame's Samehada is of comparable size to Zabuza's chopping blade, but rather than slicing its intended victim, it rips them apart like the teeth of a shark. Kisame is also the only one that is able to wield his Samehada. When Maito Gai attempted to use the Samehada against Kisame, the sword responded by attacking Gai's hand with spikes coming out of the handle.
Kisame loves to fight, and was eager to fight Asuma, Kurenai and Gai at the same time, but was disappointed when Itachi ordered a retreat. He is fearless, and not afraid to use his Samehada liberally. He uses water-based jutsus and is able to create water from nothing, turning any battleground into a lake, enabling him to use even stronger water-based jutsus. Kisame's amount of chakra is said to be the largest in Akatsuki. Truly someone to be cautious of, if not terrified of. As an Akatsuki member, Kisame was assigned to capture the host of the Four-tailed beast, an assignment he already succeeded in.