Kisame was a very tall and muscular shinobi, and was the tallest member in Akatsuki. He had a distinctive shark-like appearance, complete with pale, blue-grey skin. He also has small, round, white eyes, gill-like facial markings under his eyes, and actual gills on his shoulders, and sharp triangular teeth, much like the other members of the Seven Swordsmen of the Mist. He also styled his blue hair in the form of a shark fin. As a member of Akatsuki, he also wore dark-purple nail polish and he donned the typical black cloak members of Akatsuki wore, and underneath it he was bare-chested while wearing beige pants and ankle-high sandals. He also wore a brown sash across the front and back of his cloak to hold Samehada in place. He wore his Akatsuki ring on his left ring finger, bearing the kanji for "south" which was yellow in color.
Kisame loves to fight and loves to fight stronger opponents, making his thirst for battle all the more sweater. He is also quite sadistic, brutal, violent and demonstrates no hesitation in mutilating his opponents, as seen when he suggested cutting off Naruto's legs to make him easier to carry and to prevent the latter from escaping on foot. Despite his aggressive nature, Kisame is very perceptive and keen mind in battle, able to deduce the basics behind an opponent's technique and react to any potential danger he is aware of. Also, being paired with Itachi, Kisame is usually unable to finish or even start his battles with Itachi around, because the latter doesn't enjoy fighting as much as Kisame does. He would often inform his opponents that they "don't know how lucky they are". Kisame also has a deep loathing for Might Guy since their first encounter, with Guy's inability to remember Kisame prior to his death agitating him.
Originally when first partnered, Kisame warned an equally hostile Itachi to be careful of him. But in time, Kisame became one of the few members of Akatsuki that got along well with his partner despite the fact they had opposite personalities. The only common ground between both ninja being that they betrayed those close to them, Kisame was loyal to Itachi as he would only take action after being ordered to or after being given permission by him. Despite his pride, Kisame acknowledged Itachi as the stronger of the duo, evident by Kisame saying to Itachi that he himself couldn't defeat Jiraiya, but stated his certainty that Itachi could go one-on-one with the Sannin. Although he wasn't above reprimanding Itachi for being reckless with his Mangekyo Sharingan. In the Naruto anime, Kisame appeared saddened upon hearing of Itachi's death. Kisame ultimately considered Itachi as a good friend, even thinking of him in his last moments. Kisame's loyalty to Itachi is so great even Zetsu thought he only stayed in Akatsuki because of Itachi and couldn't help but wonder if Kisame would stay with the organization with Itachi dead.
Kisame was motivated to help in completing the Project Tsuki no Mei plan because of his own disillusionment with the world he lived in. He never felt as though he had a place or knew who he truly was as he was often ordered to undertake gruesome missions such as killing his own comrades. As such, he came to the conclusion that his entire life has been a lie. His partner Itachi has noted that he was a rogue that was unable to find a place for himself, something he himself may have understood because of his own treacherous past.
Kisame had a playful and morbid sense of humor and would often make light of serious situations while sporting a sadistic grin. This trait would even show during his fights as he would often mock his opponents as seen in the cases of Killer B and Guy. Upon hearing of the death of Hidan and Kakuzu, he referred to them as the "Zombie Brothers" in reference to their longevity.
Kisame was also shown to be honest and humble to his comrades, especially Itachi, as shown when Itachi reprimanded him for taking so long to capture Roshi. Although defending himself by saying Itachi had no idea how powerful Roshi was, Kisame quickly admitted he asked to capture Roshi alone. He was also a very appreciative person. When Obito had disguised himself as a useless, incompetent, and clumsy person and having no idea of who he really was at the time, he still enjoyed his upbeat nature as he thought he livened up the mood of Akatsuki's meetings. He also reprimanded Tobi for taking so long to come clean that he was in fact alive after most of the members believed he died from Deidara's C0 suicide attack.
Other than believing everything he knew was a lie and desiring to see Tobi's "world of truth", Kisame lived strictly to protect valuable information as reflected in killing the Cypher Division to keep their Intel from the Hidden Leaf and executing Fuguki for selling their village's secrets; on a related note, he refused to bond with his team-mates when they were on a mission together. This ideal became his philosophy, ultimately motivating his assisted suicide when left with no other choice. His actions made Yamato have difficulty believing he died so nobly, despite having witnessed his death with his own eyes.
Kenjutsu Master: As his specialty, Kisame was a very powerful swordsman, and favored the use of brute strength and melee fighting in battle. Originally, Kisame wielded a normal katana, with which he was proficient enough to kill all of his comrades on one mission. After slaying his master with the said katana, Kisame's signature weapon became Samehada, a sentient, scale-covered sword, that shaves flesh instead of cutting it. Samehada is also capable of detecting and absorbing chakra upon contact. However, it seems to be unable to automatically absorb ambient chakra, judging by the fact that all instances in which it has used the ability have either been when the opponent had a visible aura around them or when direct physical contact had already been established. When Samehada absorbs chakra, its scales grow and it slowly begins to unwrap itself, revealing a mouth with several rows of shark-like teeth. Kisame could heal injuries and replenish his chakra by temporarily fusing with Samehada. He could also fuse fully to further increase his power, and expanding upon his shark-like appearance. When fused with Samehada, he gains the ability to breathe underwater using gills which form on his neck. While using his Water Prison Shark Dance Technique, he could take full advantage of that ability by drowning his opponents while remaining unharmed. In this form he can sense other people's chakra, and absorb it just by touching the foe with any part of his body. He can also hide within Samehada, which he states is flawless due to the fact that he and Samehada have identical chakra, to the extent that not even sensors can detect him.
Initially, only Kisame was able to wield Samehada; if anyone besides him tried to pick it up, spikes protruded from its handle, and it returned to Kisame's side. Samehada's loyalty seems to be due to the sword's liking of Kisame's chakra. If it finds a ninja with better chakra, it may betray it's owner in favor of the new ninja, as demonstrated when Samehada protected Killer Bee from Kisame's attempt to slash off his legs. Despite its wavering loyalty, Kisame was capable of wielding Samehada against its will. Chojuro describes the Samehada as the most terrifying sword of the Seven Ninja Swordsmen blades.
Nature Transformation: Kisame was a master of Water Release techniques, being able to alter an entire battlefield by create a large volume of water to give him the field advantage, and to use for attacks. Kisame's shark-like attributes carried over into techniques, for he even shaped his Water Style attacks into sharks. He could also use this skill as a means for transportation, riding inside of a water shark. Against stronger opponents, he increased his field advantage even further by creating a giant dome of water around himself, forcing his opponents to battle him underwater.
Summoning Jutsu: In keeping with his shark theme, Kisame had shown the ability to summon sharks for both battle and message sending purposes, and can combine the one summoned shark with the Water Style: Thousand Hungary Sharks as a way to conceal the messenger shark location and allow it to escape. He also used them with the Water Prison Jutsu to commit suicide.
Immense Strength: Kisame displayed raw speed and immense physical strength, being able to overwhelm even Guy, an extraordinary taijutsu master, during their second battle. With a single punch, Kisame smashed Guy to the bottom of the lake and displaced the water around the area. He also overpowered another skilled melee-weapon user, Asuma Sarutobi, using only the tip of Samehada (wielded with one hand) against Asuma's two blades, which were held overhead with his body as extra support.
Immense Endurance: Kisame also had matching durability and endurance, being able to survive Killer Bee's "Version 2" Lariat (albeit his ribcage was completely destroyed), as well as what was usually a one-hit instant kill technique from Guy. After the latter, he retained enough strength to break free of Yamato's chakra-suppressing wood restraints, further demonstrating his raw strength and endurance.
Enhanced Speed: Aside from his raw strength, he possesses raw speed that outmatches Guy's, and even able to overwhelm him during their fights. He also demonstrated especially fast hand seal prowess.
Expert Hand-to-Hand Combatant: Unlike his partner Itachi, Kisame preferred direct physical combat, with which he has repeatedly been shown to be very proficient and dangerous. Generally while fighting, he combined strong taijutsu strikes with powerful slashes from Samehada.
Immense Chakra Power: Kisame had a massive amount of chakra, even by Akatsuki standards. Karin, upon sensing Kisame, stated she had never seen so much chakra in one place. Even when he fought at 30% power in one instance, Neji compared his chakra supply to that of Naruto; at such an instance, Kisame was able to transform a dry wasteland into a small ocean. Chojuro claims that Kisame is a "Tailless Tailed Beast", due to his superhuman chakra level and combination with Samehada. Aside from his own massive reservoir, Kisame could absorb chakra even without using Samehada. Aoba Yamashiro discovered this when he used his Secret Technique Stone Needles in an attempt to paralyze Kisame, who instead just sucked the chakra through the threads and exhausted him. He can even steal chakra from Samehada by simply grabbing onto it. His chakra is light-blue in color.