Head of the Hyūga Clan
Being an identical twin, Hiashi is a mirror image of his brother Hizashi with the exception of an unmarked forehead. He has long, black hair (sometimes depicted as brown in the anime), and featureless white eyes like all members of his clan.
Hiashi made a non-speaking role when Lee and the others visit Neji's house.
Though he has not been shown in real combat in the spin-off, as the head of Hyuga clan, he is presumably skilled as he possesses the kekkei genkai Byakugan which granted him near 360 degrees of vision.