Zaku Abumi was a Genin-level ninja from Otogakure. He was part of the team that took the Chunin exam in order to assassinate Sasuke Uchiha. Like many Sound ninja, he has been physically altered with unnatural enhancements that enhance his abilities; in his case, he was fitted with hollow air tubes that extend through his arms and open through his hands, allowing him to propel a combination of air pressure and sound in various ratios, controlled by his chakra. Unlike his partners, a glance into his past and how Orochimaru recruited him was given, making him a far more dramatic character. The anime shows that he was an orphan living on the streets who hustled by stealing for a living, and was almost always beaten for it. Orochimaru had told him he had potential and liked the strength in his eyes. He refuses to give up, even at the cost of his own life. After saving his partner Dosu from Rock Lee's lotus attack, he brutally fought off Sakura who attempted to prevent him from killing Sasuke. After the helpless Sakura lay beaten on the ground, he and his team had to fight Team Asuma. During the fight, Sasuke finally regained consciousness, and asked Sakura who had injured her. Zaku took the credit, and Sasuke proceeded to dislocate and greatly injure Zaku's shoulders. He was the only Sound ninja to fight Sasuke, as the others retreated. During his fight with Shino Aburame in the preliminary exams, he overcame the injuries to his shoulders and was able to use his arms to defend himself against Shino. Due to his cockiness, he attempted to attack both Shino and his approaching army of Kekai insects, not noticing that the chakra-eating bugs had already filled the tubes in his arms, preventing him from attacking and even more brutally crippling and preventing him from doing any damage in the future (In the manga, his right arm was blown off due to the kikai bugs Shino used to fill up Zaku's air tubes, and the left was kept intact but halfway sliced. In the anime both of his arms are left intact, but have numerous holes in them, achieving the same, albeit less gruesome, result). Dosu says he would avenge him (or rather, his severed arms), but failed to do so. Zaku, along with Kin Tsuchi, is later murdered as a sacrifice for Orochimaru's Impure World Resurrection for the First and Second Hokages against the Third Hokage. (Source: Narutopedia)
Yoroi is a member of Kabuto's team posing as a group of Leaf Ninja. He uses his chakra absorption technique to drain the chakra of an opponent, leaving them too weak to fight. He is defeated by Sasuke during the first round of the chunin exams.
Tekka Uchiha (���テッカ, Uchiha Tekka) was a member of the Konoha Military Police. He questioned Itachi about the apparent suicide of Shisui Uchiha with Inabi Uchiha and Yashiro Uchiha. He was killed by Itachi along with the rest of the Uchiha clan. (Source: Narutopedia)
Inabi Uchiha (���イナビ, Uchiha Inabi) was a policeman of the Konoha Military Police and a member of the Uchiha clan. He and two other officers, Yashiro and Tekka Uchiha, questioned Itachi Uchiha about his whereabouts during the time when Shisui Uchiha supposedly committed suicide. Itachi replied, very irritated, making it to the list of suspects brought. Inabi was then killed by Itachi in the Uchiha Clan Massacre. (Source: Narutopedia)
Shisui Uchiha (���シスイ, Uchiha Shisui) was feared as "Shisui of the Body Flicker" (瞬身�シスイ, Shunshin no Shisui) and was one of the most talented of the Uchiha clan. Shisui was the best friend of Itachi Uchiha; in fact, Itachi thought of him as an older brother. He was found drowned in a river from what appeared to be suicide, though the Konoha Military Police believed it to be murder. It was later revealed that Shisui had been ordered to keep tabs on Itachi. Itachi later admitted to Sasuke Uchiha that he had murdered Shisui to obtain the Mangeky� Sharingan, forging Shisui's handwriting on his suicide note with the help of the Sharingan. Shisui acquired the Mangyek� Sharingan and a technique called Kotoamatsukami. Shisui wanted to stop the Uchiha's Coup d'Etat against Konohagakure with his Kotoamatsukami, but Danzo stole one of his eyes and so he gave his other eye to Itachi to protect the village and jumped off a cliff and died, then later found on the river by the Uchiha military policemen. His eye helped Itachi to free him self from Kabuto's Reanimation control. (Source: Narutopedia)
Fuu (フウ) was a kunoichi from Takigakure and the jinchuuriki of Choumei, the Seven-Tails. Choumei has been captured and sealed by Akatsuki, causing her death when the beast was extracted. Upon her reincarnation, Choumei appears to have been resealed within Fuu. (Source: Narutopedia)
Han (�ン) was a shinobi from Iwagakure and was the host of the Five-Tailed Beast, as well as the physically largest jinchuuriki, easily standing a head taller than Kirabii. The Five-Tails has been captured and sealed by Akatsuki, causing this jinchuuriki's death when the beast was extracted. Another jinchuuriki, named Roushi, who held the Four-Tailed Beast, also originated from Iwagakure. It is logical to assume that he and Roushi knew each other as they were both jinchuuriki of the same village. (Source: Narutopedia)