Hizashi Hyūga

was a member of the Hyuga Clan. He was the father of Neji Hyuga, twin brother of Hiashi Hyuga, and uncle of Hinata and Hanabi Hyuga.

Background
Hizashi Hyuga was Hiashi Hyuga's twin brother, but as he was born seconds later, Hiashi was made the successor to the clan. At some point in Hizashi's life, he was branded with a curse mark that could be used to punish him if he disobeyed the main branch, and would seal the Byakugan when he died.

He eventually fathered a son, Neji. On Hinata's third birthday, Hiashi branded Neji with a curse mark. At this time, Hizashi was aware of Neji's talent, and began to resent that Neji would be forced to serve the main household. When he gave Hinata a glance filled with murderous intent, Hiashi responded by activating Hizashi's curse mark, then coldly told Neji that he must not forget his duties.

Death and Legacy
After Hiashi killed the head ninja from the Land of Lightning to save Hinata, the Land of Lightning demanded his body, claiming to want it as restitution- in reality, they wanted to obtain the Byakugan. At this point, the clan elders proposed sending Hizashi's body in Hiashi's place, ensuring that the Byakugan's secret would not be discovered.

While Hiashi refused, and insisted on offering himself instead, he learned that Hizashi had already agreed. Hizashi disabled Hiashi with a single blow when he tried to stop him, then calmly stated that while he still hated the head family, he chose death to save his brother, to prevent war and to decide his destiny. He asked Hiashi to tell Neji of his reason for his decision, regretting that he had shown Neji his bitterness in life. Hiashi chose not to tell Neji until he was mentally ready, and Hizashi's death led to Neji's blaming the main house and believing that fate cannot be changed. Neji eventually learned the truth after being defeated by Naruto in the finals of the Chunin Exams, and in the anime, read his father's final letter. Upon realizing this, Neji forgave the main family, and silently told his father of his new dream to never lose again.

Trivia

 * Hizashi's death is mentioned briefly when the Raikage complains that Konoha has taken too long to eliminate Sasuke Uchiha, noting that "They certainly dealt with Hyuga swiftly enough," possibly unaware that Hizashi willingly cooperated to be killed in Hiashi's place, while Sasuke is trying to avoid being found by the Leaf ninja.