Rin Nohara

Rin was a medical-nin and the teammate of Kakashi Hatake and Obito Uchiha under the Fourth Hokage in the Kakashi Gaiden exclusive.

Role In Kakashi Gaiden
She was a sweet and friendly girl who cared for her teammates. She had intimate feelings for Kakashi, but he ignored her. In turn, Obito had a crush on her but she ignored him.

When Rin was captured by enemy shinobi from Iwagakure no sato, Obito and Kakashi went to go save her, though it takes some prodding to get Kakashi to help.

Later, half of Obito's body is crushed by a rockslide in an attempt to save Kakashi. At Obito's request, Rin implants Obito's remaining Sharingan eye into Kakashi's left eye socket. (Kakashi's left eye had been destroyed in an earlier battle) Kakashi then vows to protect her with his life, at Obito's request.

Her status is currently unknown, but she is presumed dead as Kakashi has told Sasuke that everyone close to him is dead.

Trivia
One possible meaning of her name means "cold". More likely, however, Rin is one of the readings of the kanji hayashi, for forest/woods. Usually when used for a girl's name it's written with the kanji for suzu, or a small bell. Other characters from Konoha have names related to trees or leaves (such as Sakura, Shino and many of the supporting character villagers) so it is probably the former meaning (though the latter does recall the bells used in the training by Sarutobi, and Kakashi in the series).