Yashamaru

was a medic-nin, the younger brother of Karura, and thus the uncle of Temari, Kankurō, and Gaara.

Background
After his sister was sacrificed to seal the One-Tailed Shukaku, Yashamaru began taking care of Gaara. At first, Gaara thought that Yashamaru was the only one that cared about him. Yashamaru taught Gaara about physical pain, emotional pain, and love, concepts Gaara was completely unaware of in his childhood. In reality, however, Yashamaru hated Gaara, never having been able to get over the loss of his sister. When the Fourth Kazekage asked him to assassinate Gaara, Yashamaru willingly accepted the command in order to avenge Karura. The assassination attempt, however, ended in a desperate suicide mission and ultimately failed. His suicide bombing attempt on Gaara's life caused Gaara to become somewhat psychotic. Yashamaru's last words, to Gaara, were, "This is it. Please die." This left Gaara even more of an emotional wreck than he already was.

Trivia

 * In the Polish, Brazil and Italian versions of the Naruto manga, Yashamaru is portrayed as female rather than male. Even in the English anime, there is no clear indication of his gender.
 * Yashamaru's name, 夜叉丸, is composed of three Kanji. The first two, Yasha (夜叉) refer to creatures in Japanese mythology known as "Night Demons" (See Yaksha ). The Hindu version of the Yakshas usually portray them as having two sides: a darker, more sinister side, and a benevolent, lovable side. Yashamaru's betrayal could be a reference to this "dark side" of Yakshas. Maru (丸) is a common ending for male names.
 * Yashamaru, along with many other characters within the naruto saga, made a cameo in the ending omake of Shippūden episode 129.