Yagura Karatachi

Little is known about this Jinchūriki yet. She hailed from Kirigakure and on the Chapter 420 cover, seemed to be the host of the Three-Tailed Beast. However, when Deidara and Tobi fought the Three-Tails, Deidara claimed the beast was weak because it had no host. This might possibly be because this Jinchūriki died.

Speculation
It is suggested that she is a relative of Yukimaru, as they both have similar appearances. Also, it's been said that Yukimaru can control the three-tailed beast.