Hiashi Hyūga

is the head of the Hyūga clan. He is the father of Hinata and Hanabi Hyūga, the older twin brother of the late Hizashi Hyūga, and the uncle of Neji Hyūga.

Background
Hiashi was born seconds before his twin brother Hizashi, making Hiashi the head of the Hyūga clan and Hizashi the member of the branch house, whose only purpose in life would be to protect members of the main house. Years later, when Neji was born, Hizashi became bitter that his son would never be able to reach his full potential like a member of the main house, causing him to be openly resentful of Hiashi and his daughter. Hiashi was also responsible for branding a curse mark on Neji, further straining the relationship between the two brothers. When Hizashi gave Hinata a murderous glare, Hiashi activated the curse seal on his younger brother, causing him intense pain, and coldly told Neji to not forget about his duties.

During a visit to Konoha by a Head Ninja of Kumogakure, who had come to the village to sign a peace treaty, a young Hinata was kidnapped. Hiashi saved her by killing her kidnapper, only to discover that it was the Kumogakure ambassador. Kumogakure demanded Hiashi's head in return for the life he had taken, or risk resuming open warfare between the two villages. Konoha, wishing to avoid another conflict, was compelled to comply, but was not willing to fulfill Kumogakure's desire of getting to study the Byakugan. The Hyūga clan elders suggested that Hizashi be used as a body double, since his Cursed Seal would seal off his Byakugan upon his death. Although Hiashi tried to find an alternative, Hizashi insisted, saying that he would finally get to choose his own fate (to make up for his wrongdoings against Hiashi), and that he could save his brother's life. Before going to his death, he asked Hiashi to someday tell Neji about why he had made his decision.

Originally, Hiashi had trained Hinata to become the successor of the Hyūga Clan. However, Hinata's lack of confidence ultimately led him to deciding she was not worthy, leading him to instead turn his attention to his younger daughter, Hanabi, while leaving Hinata in Kurenai Yuhi's care.

Personality
Hiashi's general personality is very stern and strict, as he assigns both his daughters arduous training, and rarely compliments their performance. This is especially true with Hinata; when she was assigned to Kurenai Yuhi, he told her that he was unconcerned about the possibility that she would die, saying that the Hyūga clan had no use for a weak successor. In truth, it was not that he felt Hinata's talent or potential was weak, but her drive to succeed was too weak for her to be the successor of the Hyūga clan. As the series progressed, and she started to show her true dedication, he began to openly cheer her on. Hiashi was also very strict with his younger brother and nephew, and was willing to use the Cursed Seal to punish any disobedience. However, he truly cares for them as part of the family.

Chūnin Exam arc
Hiashi made his first debut in Kurenai's flashback, when she was watching Hinata's and Neji's match in the preliminary matches of the Chūnin Exams. Hiashi debuted for the first time (in person) with Hanabi, watching Neji's match during the final rounds. He was amazed that Neji had been able to learn the main house's secret techniques by himself, but was disappointed by Neji's resentment of the main house, and his strong belief in fate. After Neji lost to Naruto, and seemed to have found himself at a crossroads in his life from Naruto's words, Hiashi decided to tell him about the circumstances surrounding Hizashi's death. Although Neji did not initially believe him, Hiashi's bowing to him for forgiveness showed him that it was true.

Invasion of Konoha arc
Hiashi assisted in the defense of Konoha during the invasion by Sunagakure and Otogakure, repelling invaders with Eight Trigrams Palms Heavenly Spin.

Anime filler arcs
In the anime's filler arcs, Hiashi, realizing separating the Hyūga clan into two houses was causing a huge rift in the clan, decided, as head of the clan, to try and mend this. He began training Neji regularly in their clan's full arts, something that was already considered a taboo by the rest of the main house. His relationship with Hinata was shown improving, as he encouraged her to do her best after seeing her be more confident in herself.

Naruto Special: Finally a Clash Jounin VS Genin
Standing behind his youngest daughter Hanabi Hyūga before the start of the event.

Invasion of Pain arc
Although he has yet to make an appearance in Part II, Hiashi was noted to be away with Hanabi during Pain's attack on Konoha. He left Hinata's protection to Kō Hyūga during his absence.

Abilities
As a member of the Hyūga clan, Hiashi possesses the Byakugan, which gives him an almost 360-degree field of vision, except for a small blind spot at the back of the neck. Also, as the head of his clan, he is well-versed in all of his clan's secret techniques. While the full extent of his prowess remains unknown, during Orochimaru's invasion, Hiashi demonstrated tremendous skill by repelling several Sound and Sand ninja away with one Eight Trigrams Palms Heavenly Spin. He also showed his great skill of taijutsu when he killed the Kumogakure ambassador with one hand, striking him in the stomach. He only did this to save Hinata.

Trivia

 * In English dub, the english voice for Hiashi also does the voice for his twin brother, Hizashi.