Kō Hyūga

is a shinobi of Konohagakure and a branch member of the Hyuga clan.

Invasion of Pain
He is the protector of Hinata when Pain attacked Konoha, because Hanabi and Hiashi Hyuga were on a mission. As Hinata tried to help Naruto, Kou called her back claiming that she would only be a burden to him.

Byakugan
As a member of the Hyuga clan, Kou has the ability to use the Byakugan to his advantage. In the Invasion of Pain arc, he uses the Byakugan to see Naruto fighting Pain.

Trivia
Kou is the first Hyuga clan member seen so far with blonde/white hair.