In the epic Mahabharata, Uttar or Uttara(उत्तर), the prince of Matsya Kingdom and the son of King Virata, at whose court the Pandavas spent a year in concealment during their exile. He was brother of Uttarā and husband of Keesavi, the daughter of King Srilajan.
Towards the end of the year that the Pandavas spent at the Matsya kingdom, Duryodhana attacked Matsya and brought the army of Hastinapura to their borders. King Virata had already taken his entire army to another battle, so Uttar alone went to confront Duryodhana's army with Arjuna(disguised as the eunuch danseuse Brihannala) as his charioteer. While initially Uttar was confident of his abilities, he panicked upon seeing the congregation of renowned warriors at the head of Duryodhana's forces, particularly Bhishma, Drona, Kripa, Karna, and Asvatthama. Uttar dismounted the chariot and ran for his life, but Arjun gave chase and caught him, telling him off for such a show of cowardice unbecoming of a crown-prince. Arjuna then revealed his true identity to Uttar who was incredulous and believed Arjuna only when he recited his ten aliases. Arjuna then took charge and single-handedly and defeated the entire Hastinapura army in a spectacular show of his masterful archery. After this experience, Uttar gained much courage.
Uttar fought at the Pandavas' side and was killed by Shalya on the first day of the Kurukshetra war. On that day, Keesavi gave birth to a child which was born dead. He had two brothers who also fought at the Pandavas' side. One was Shweta, who too was killed on the first day. When he started attacking Shalya repeatedly to avenge his brother's death, Bhishma came to his rescue and ultimately killed him. The other one was Shankhya, who was killed by Drona on the seventh day of the war.