Mū

A Kage ressurected by Kabuto for the Fourth Great Shinobi War, Which country he originated from is unknown.

Appearance
His body appears to be covered in bandages with only a triangle of flesh including his eyes and nose showing. He wears a dark coloured headband with no markings.

Possible Origin
While his origin is unknown, the possiblities are limited due to a number of factors.

Hokage - This is impossible as the identities and appearances of all previous Hokage are well known throughout the series and this figure matches none of them.

Mizukage - While Yagura was also revived as a member of the Jinchuriki, this still leaves the Possibility of him being any one of the first three Kage of the Hidden Mist.

Kazekage - His appearance does not seem to coincide with any of the Kazekage statues in the Hidden Sand village, but given the statues are all adorned in formal robes with only the first wearing any kind of face covering, it doesn't eliminate the possibility of him being one of the first three here as the Fourth Kazekage was also revived.

Raikage - Of the Raikage, the Third was revived, but this still leaves the possibility of this Kage being either the First or Second Raikage.

Tsuchikage - With Onoki currently being the oldest living Kage and the latest of the Tsuchikage as he refused to choose a sucessor it leaves the possibility of this man being either the First or Second Tsuchikage.